Holothuria+leucospilota

**Black Sea Cucumber** **//Holothuria (Mertensiothuria) leucospilota// (Brandt, 1835)**



Overview | Distribution | Morphology | Potential Value | Conservation Status | Taxonomy & Systematics | Molecular Biology | Glossary | Additional Information | References =**Overview** = //Holothuria (Mertensiothuria) leucospilota// is a marine invertebrate, with a dark brown (almost black) body surface. It is approximately 40 to 50cm in length when full-grown, but can be elongated to almost a metre long 1]. It has a soft and pliable, cylindrical body covered with soft papillae 2].

**Why are we interested in them?**
**Ocean acidification** has severely impacted coral reefs worldwide as a result of increasing CO 2  levels and decreasing pH in seawater. This has caused the dissolution of calcium carbonate (CaCO 3 ) that has severely affected reef-building organisms including corals and calcifying macroalgae.

A study by Schneider et al. has shown that //Holothuria leucospilota// as deposit feeders, ingest carbonate sand and rubble through their digestive tract and dissolves the sediment CaCO 3  as part of their digestive processes 3]. Such activity allows for natural CaCO 3  turnover and increased alkalinity, as the sea cucumber secretes ammonia (NH <span style="font-family: Georgia,serif; vertical-align: sub;">3 <span style="font-family: Georgia,serif; font-size: 120%; vertical-align: sub;">, <span style="font-family: Georgia,serif; font-size: 120%;">which becomes NH <span style="font-family: Georgia,serif; vertical-align: sub;">4 <span style="font-family: Georgia,serif; font-size: 120%; vertical-align: super;">+ <span style="font-family: Georgia,serif; font-size: 120%;"> in the aqueous medium) as a by-product of their digestive process. They contribute to the nutrient cycling process and enhance productivity in coral reefs, while buffering the seawater pH from ocean acidification 3]. Thus, //Holothuria leucospilota// can reduce the impact that ocean acidification has on coral reefs!

<span style="color: #9830cc; font-family: Georgia,serif; font-size: 120%;">How do they feed?
<span style="font-family: Georgia,serif; font-size: 16px;">//Holothuria leucospilota// are **epibenthic, deposit feeding** sea cucumbers. They actively feed on organic material in the sediment throughout the day using their oral tentacles 4]. Although they are often viewed as indiscriminate feeders, a study by Ong Che (1990) 5], has shown that this species actively selects smaller-sized grains and the selectivity is consistent across different substrate types. Their feeding habits are important for the **bioturbation** of marine sediments as they swallow a significant amount of sand, which eventually passes through the gut. For a closer look at their feeding tentacles, watch this video below!

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<span style="color: #9830cc; font-family: Georgia,serif; font-size: 120%;">How do they defend themselves?
<span style="font-family: Georgia,serif; font-size: 16px;">Sea cucumbers, as well as other echinoderms including sea stars (Asteroidea), brittle stars (Ophiuroidea) and sea urchins (Echinoidea) carry out autotomy as a form of self-defense 4]. **Autotomy** is an extreme form of self-defense where the organism amputates its own body appendages or organs in response to stress 4].

<span style="color: #000000; font-family: Georgia,serif; font-size: 16px;"> In the case of //Holothuria leucospilota//, the s <span style="font-family: Georgia,serif; font-size: 16px;">pecies i <span style="color: #000000; font-family: Georgia,serif; font-size: 16px;">s capable of evisceration (a specialized form of autotomy). This process involves rupturing its **cloaca** and ejection of its internal organs including the gut, gonadal tubes and the respiratory trees 6,7]. A study by Hsieh (2012) has shown that approximately 28% of its body mass is eviscerated regardless of the organism size 4]. The same study showed that organ regeneration post-evisceration started with the thickening of the mesentery lining on the inner wall cavity as well as the thickening of the **cuvierian tubules**. This was then followed by the thickening of the digestive tract.

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<span style="color: #982fcc; font-family: Georgia,serif; font-size: 120%;">**How do they reproduce?**
<span style="font-family: Georgia,serif; font-size: 16px;">//Holothuria leucospilota// have 2 modes of reproduction. They generally undergo asexual reproduction by **transverse fission** (Fig.2), although they are also capable of sexual reproduction 8,9]. Closer inshore and shallow-water, populations are denser and hence consist of smaller individuals that reproduce mainly by transverse fission.

<span style="font-family: Georgia,serif; font-size: 16px;">A study conducted in Darwin, Australia, has shown that fission could occur regardless of the maturity stage of individuals 10]. On the other hand, scattered individuals from deeper or outer reef populations are larger and they reproduce sexually 11]. Sexual reproduction is characterized by “**dioecism**, external fertilization and a planktonic larval stage” [9,10]. The reproductive period of //H. leucospilota// is affected by environmental factors including water temperature and the timing of food resources 12]. In southern Taiwan (located at the northern limits of the tropics), //H. leucospilota// has an annual reproductive season, in late spring or summer, where environmental conditions are optimal for the development of planktonic larvae 12].



<span style="color: #9831cc; font-family: Georgia,serif; font-size: 120%;">**What parasite lives in them?**
<span style="font-family: Georgia,serif; font-size: 16px;">//Holothuria leucospilota// is the specific host to the **parasitic worm pearlfish** (//Encheliophis vermicularis//). A study by Miyazaki et al. (2014) has suggested that pure saponins or triterpenoidal glycosides of the sea cucumber chemically attracts the pearlfish 13]. The fish enters the coelomic cavity of the sea cucumber via the anus without causing exudation of the cuvierian tubules 14]. It then lives within the gut of the sea cucumber and feeds on its internal organs including the respiratory tree and gonads 15]. Interestingly, the sea cucumber is able to “void their internal organs and subsequently regenerate them” 16]. It was also suggested that to minimize damage to their hosts, these pearlfishes move from one host to another 16].

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= <span style="color: #7823a0; font-family: Georgia,serif; font-size: 130%;">**Distribution** =

<span style="color: #982fcc; display: block; font-family: Georgia,serif; font-size: 120%; text-align: left;">**Where can they be found globally?**
<span style="display: block; font-family: Georgia,serif; font-size: 16px; text-align: left;"> This species is widespread throughout the Indo-Pacific and the Red Sea. It can be found from South Africa to India, China to Australia, Hawaii, Polynesia, and east to Central America from Mexico to Peru 17]. The range map can be found here.

<span style="color: #982ecc; display: block; font-family: Georgia,serif; font-size: 120%; text-align: left;">**Where can they be found in Singapore?**
<span style="display: block; font-family: Georgia,serif; font-size: 16px; text-align: left;"> In Singapore, //Holothuria leucospilota// is not common and is patchily distributed 18]. It is often found in the southern islands of Singapore as illustrated in the map below (Fig.3).

<span style="color: #982ecc; display: block; font-family: Georgia,serif; font-size: 120%; text-align: left;">**What habitat do they live in?**
<span style="display: block; font-family: Georgia,serif; font-size: 16px; text-align: left;">//Holothuria leucospilota// is widely distributed on reef flats throughout the tropical Indo-West Pacific 19]. It is usually found with its body partially hidden under large boulders or rocks 20]. It is also generally found in shallow waters, up to depths of up to 10m 21].

= <span style="color: #7823a0; font-family: Georgia,serif; font-size: 130%;">**Morphology** =

<span style="font-family: Georgia,serif; font-size: 120%;">Sea cucumbers or holothurians have orally-aborally elongated bodies and their gut lies in a **<span style="font-family: Georgia,serif; font-size: 120%;">coelomic cavity **<span style="font-family: Georgia,serif; font-size: 120%;">. Since they are invertebrates, they do not possess a backbone but they have reduced microscopic ossicles known as **<span style="font-family: Georgia,serif; font-size: 120%;">spicules **<span style="font-family: Georgia,serif; font-size: 120%;"> on their body wall. Their mouth is encircled by **<span style="font-family: Georgia,serif; font-size: 120%;">tentacles **<span style="font-family: Georgia,serif; font-size: 120%;"> and the **<span style="font-family: Georgia,serif; font-size: 120%;">anus **<span style="font-family: Georgia,serif; font-size: 120%;"> is often edged by **<span style="font-family: Georgia,serif; font-size: 120%;">papillae **<span style="font-family: Georgia,serif; font-size: 120%;"> 11]. **Oral tentacles**, primarily for feeding, are enlarged and modified tube feet that can either be <span style="font-family: Georgia,serif; font-size: 16px;">dendritic (branching in an arborescent manner), peltate (flattened and shield-like), <span style="font-family: Georgia,serif; font-size: 120%;">pinnate (feather-like) or <span style="font-family: Georgia,serif; font-size: 16px;">digitate (finger-like projections) <span style="font-family: Georgia,serif; font-size: 120%;">(Fig.5).



<span style="font-family: Georgia,serif; font-size: 120%;">They often lie on the substrate with their ventral surface (or **<span style="font-family: Georgia,serif; font-size: 120%;">trivium **<span style="font-family: Georgia,serif; font-size: 120%;">) that bears locomotory tube feet, while on their dorsal surface (or **<span style="font-family: Georgia,serif; font-size: 120%;">bivium **<span style="font-family: Georgia,serif; font-size: 120%;">), tube feet are often represented by papillae 11]. Holothurians also have a **<span style="font-family: Georgia,serif; font-size: 120%;">calcareous ring **<span style="font-family: Georgia,serif; font-size: 120%;"> that encircles the pharynx, serving as an attachment point for muscles operating the oral tentacles and for the anterior ends of other muscles that contract the body longitudinally 22]. Many large holothurians have **<span style="font-family: Georgia,serif; font-size: 120%;">respiratory trees **<span style="font-family: Georgia,serif; font-size: 120%;"> that perform gaseous exchange. The **rete mirabile** along the gut serves to distribute metabolites and nutrients throughout the organism [2]. Some holothurians possess **<span style="font-family: Georgia,serif; font-size: 120%;">cuvierian tubules **<span style="font-family: Georgia,serif; font-size: 120%;">, which are highly adhesive when ejected in water. This is part of their **<span style="font-family: Georgia,serif; font-size: 120%;">defence mechanism **<span style="font-family: Georgia,serif; font-size: 120%;"> that allows them to entangle predators.



<span style="color: #972ecc; display: block; font-family: Georgia,serif; font-size: 120%; text-align: left;">**How do we distinguish this species from other sea cucumbers?**
<span style="font-family: Georgia,serif; font-size: 120%;">To properly identify holothurians, there are several key features to be examined. //Holothuria leucospilota// can be easily identified in the waters of Singapore, although it is often misidentified as the //Holothuria atra// Jaeger, 1833 which is commonly found in the other parts of the Indo-Pacific region. For a pictorial key to confirm the identification of a sea cucumber, refer to this website. <span style="font-family: Georgia,serif;">(N.B. This pictorial key is for Northern Australian sea cucumbers. Please use with discretion depending on your region.)

<span style="font-family: Georgia,serif;"> [Information from Cannon & Silver 1986 2], Conand 1998 11] and James 1995 20]. Illustration by Conand 1998 11]. Photo of //Holothuria atra// by: © Florent Charpin (reefguide.org) Permission pending] <span style="display: block; font-family: Georgia,serif; font-size: 120%; text-align: center;"> <span style="display: block; font-family: Georgia,serif; font-size: 120%; text-align: center;"> <span style="display: block; font-family: Georgia,serif; font-size: 120%; text-align: center;"> <span style="display: block; font-family: Georgia,serif; font-size: 120%; text-align: center;">**Distinguishing features** || <span style="display: block; font-family: Georgia,serif; font-size: 120%; text-align: center;">**(Black sea cucumber)** <span style="display: block; font-family: Georgia,serif; font-size: 120%; text-align: center;">**//Holothuria leucospilota//** || <span style="display: block; font-family: Georgia,serif; font-size: 120%; text-align: center;">**(Lollyfish)** <span style="display: block; font-family: Georgia,serif; font-size: 120%; text-align: center;">**//Holothuria atra//**  || <span style="display: block; font-family: Georgia,serif; font-size: 120%; text-align: center;"> <span style="display: block; font-family: Georgia,serif; font-size: 120%; text-align: center;"> <span style="display: block; font-family: Georgia,serif; font-size: 120%; text-align: center;"> <span style="display: block; font-family: Georgia,serif; font-size: 120%; text-align: center;"> <span style="display: block; font-family: Georgia,serif; font-size: 120%; text-align: center;"> <span style="display: block; font-family: Georgia,serif; font-size: 120%; text-align: center;"> <span style="display: block; font-family: Georgia,serif; font-size: 120%; text-align: center;"> <span style="display: block; font-family: Georgia,serif; font-size: 120%; text-align: center;">**External** || <span style="display: block; font-family: Georgia,serif; font-size: 120%; text-align: center;">Form || <span style="display: block; font-family: Georgia,serif; font-size: 120%; text-align: center;">Elongate; narrow anteriorly than posteriorly; tapered towards posterior end || <span style="display: block; font-family: Georgia,serif; font-size: 120%; text-align: center;">Cylindrical, elongate; rounded ends || <span style="display: block; font-family: Georgia,serif; font-size: 120%; text-align: center;"> <span style="display: block; font-family: Georgia,serif; font-size: 120%; text-align: center;"> <span style="display: block; font-family: Georgia,serif; font-size: 120%; text-align: center;"> <span style="display: block; font-family: Georgia,serif; font-size: 120%; text-align: center;">Ventral, surrounded by 20 black, peltate tentacles || <span style="display: block; font-family: Georgia,serif; font-size: 120%; text-align: center;"> <span style="display: block; font-family: Georgia,serif; font-size: 120%; text-align: center;"> <span style="display: block; font-family: Georgia,serif; font-size: 120%; text-align: center;"> <span style="display: block; font-family: Georgia,serif; font-size: 120%; text-align: center;"> <span style="display: block; font-family: Georgia,serif; font-size: 120%; text-align: center;"> <span style="display: block; font-family: Georgia,serif; font-size: 120%; text-align: center;"> <span style="display: block; font-family: Georgia,serif; font-size: 120%; text-align: center;"> <span style="display: block; font-family: Georgia,serif; font-size: 120%; text-align: center;"> <span style="display: block; font-family: Georgia,serif; font-size: 120%; text-align: center;"> <span style="display: block; font-family: Georgia,serif; font-size: 120%; text-align: center;"> <span style="display: block; font-family: Georgia,serif; font-size: 120%; text-align: center;"> <span style="display: block; font-family: Georgia,serif; font-size: 120%; text-align: center;"> <span style="display: block; font-family: Georgia,serif; font-size: 120%; text-align: center;"> <span style="display: block; font-family: Georgia,serif; font-size: 120%; text-align: center;"> <span style="display: block; font-family: Georgia,serif; font-size: 120%; text-align: center;"> <span style="display: block; font-family: Georgia,serif; font-size: 120%; text-align: center;"> <span style="display: block; font-family: Georgia,serif; font-size: 120%; text-align: center;"> <span style="display: block; font-family: Georgia,serif; font-size: 120%; text-align: center;">**Internal** || <span style="display: block; font-family: Georgia,serif; font-size: 120%; text-align: center;">Cuvierian tubules || <span style="display: block; font-family: Georgia,serif; font-size: 120%; text-align: center;">Well- developed; very thin and long; readily ejected when it is under tactile stress || <span style="display: block; font-family: Georgia,serif; font-size: 120%; text-align: center;">Absent || <span style="display: block; font-family: Georgia,serif; font-size: 120%; text-align: center;"> <span style="display: block; font-family: Georgia,serif; font-size: 120%; text-align: center;"> <span style="display: block; font-family: Georgia,serif; font-size: 120%; text-align: center;">Calcareous ring || <span style="display: block; font-family: Georgia,serif; font-size: 120%; text-align: center;">Has large radial pieces and triangular interradials || <span style="display: block; font-family: Georgia,serif; font-size: 120%; text-align: center;">Has large radial pieces and narrow interradials  || <span style="display: block; font-family: Georgia,serif; font-size: 120%; text-align: center;"> <span style="display: block; font-family: Georgia,serif; font-size: 120%; text-align: center;"> <span style="display: block; font-family: Georgia,serif; font-size: 120%; text-align: center;"> <span style="display: block; font-family: Georgia,serif; font-size: 120%; text-align: center;"> <span style="display: block; font-family: Georgia,serif; font-size: 120%; text-align: center;"> <span style="display: block; font-family: Georgia,serif; font-size: 120%; text-align: center;"> <span style="display: block; font-family: Georgia,serif; font-size: 120%; text-align: center;"> <span style="display: block; font-family: Georgia,serif; font-size: 120%; text-align: center;"> <span style="display: block; font-family: Georgia,serif; font-size: 120%; text-align: center;"> <span style="display: block; font-family: Georgia,serif; font-size: 120%; text-align: center;"> <span style="display: block; font-family: Georgia,serif; font-size: 120%; text-align: center;"> <span style="display: block; font-family: Georgia,serif; font-size: 120%; text-align: center;"> <span style="display: block; font-family: Georgia,serif; font-size: 120%; text-align: center;"> <span style="display: block; font-family: Georgia,serif; font-size: 120%; text-align: center;"> <span style="display: block; font-family: Georgia,serif; font-size: 120%; text-align: center;"> <span style="display: block; font-family: Georgia,serif; font-size: 120%; text-align: center;">Spicules* ||= __<span style="font-family: Georgia,serif; font-size: 120%;">Tegument __<span style="font-family: Georgia,serif; font-size: 120%;">- **Tables** with circular large disc, having 8 or more holes; spire with 4 pillars, ending in a crown with a large central hole
 * <span style="font-family: Georgia,serif;">Table 1: Features distinguishing between //Holothuria leucospilota// and //Holothurian atra//. **
 * <span style="display: block; font-family: Georgia,serif; font-size: 120%; text-align: center;">
 * <span style="display: block; font-family: Georgia,serif; font-size: 120%; text-align: center;">
 * ^  ||= <span style="display: block; font-family: Georgia,serif; font-size: 16px; text-align: center;">Size || <span style="display: block; font-family: Georgia,serif; font-size: 16px; text-align: center;">Length: Commonly about 35cm (Up to 55cm) <span style="display: block; font-family: Georgia,serif; font-size: 16px; text-align: center;">Live Weight: Approximately 0.3kg (Up to 8kg) <span style="display: block; font-family: Georgia,serif; font-size: 16px; text-align: center;">Body wall thickness: About 3mm || <span style="display: block; font-family: Georgia,serif; font-size: 16px; text-align: center;">Length: Commonly about 20cm (Up to 45cm) <span style="display: block; font-family: Georgia,serif; font-size: 16px; text-align: center;">Live Weight: Approximately 0.2kg (Up to 1kg) <span style="display: block; font-family: Georgia,serif; font-size: 16px; text-align: center;">Body wall thickness: About 4mm ||   ||
 * ^  || <span style="display: block; font-family: Georgia,serif; font-size: 120%; text-align: center;">Tegument || <span style="display: block; font-family: Georgia,serif; font-size: 120%; text-align: center;">Very smooth || <span style="display: block; font-family: Georgia,serif; font-size: 120%; text-align: center;">Smooth, often covered in sand ||
 * ^  || <span style="display: block; font-family: Georgia,serif; font-size: 120%; text-align: center;">Mouth || <span style="display: block; font-family: Georgia,serif; font-size: 120%; text-align: center;">Ventral, surrounded by 20 black, peltate (flattened and shield-like) tentacles [[image:PA250150.JPG width="254" height="174" align="center"]] || <span style="display: block; font-family: Georgia,serif; font-size: 120%; text-align: center;">
 * ^  || <span style="display: block; font-family: Georgia,serif; font-size: 120%; text-align: center;">Anus || <span style="display: block; font-family: Georgia,serif; font-size: 120%; text-align: center;">Sub-dorsal || <span style="display: block; font-family: Georgia,serif; font-size: 16px; text-align: center;">Terminal ||
 * <span style="display: block; font-family: Georgia,serif; font-size: 120%; text-align: center;">
 * ^  || <span style="display: block; font-family: Georgia,serif; font-size: 120%; text-align: center;">
 * ^  ||= <span style="display: block; font-family: Georgia,serif; font-size: 120%; text-align: center;">

<span style="display: block; font-family: Georgia,serif; font-size: 120%; text-align: center;">- **Buttons** are regular (with 6 or 8 holes) or irregular

__<span style="font-family: Georgia,serif; font-size: 120%;">Ventral podia __<span style="font-family: Georgia,serif; font-size: 120%;">- Large plates with many holes



__<span style="font-family: Georgia,serif; font-size: 120%;">Dorsal podia __<span style="font-family: Georgia,serif; font-size: 120%;">- Long rods

__<span style="font-family: Georgia,serif; font-size: 120%; line-height: 1.5;">Tentacles __<span style="font-family: Georgia,serif; font-size: 120%;">- Few rods ||= __<span style="font-family: Georgia,serif; font-size: 120%;"> Tegument __<span style="font-family: Georgia,serif; font-size: 120%;">- **Tables** with circular disc showing 8 holes (4 central and 4 smaller holes in between) and a spire of 4 pillars ending in a maltese crown

<span style="display: block; font-family: Georgia,serif; font-size: 120%; text-align: center;">- **Rosettes** are small and simple; more abundant in ventral tegument __<span style="font-family: Georgia,serif; font-size: 120%;">Ventral podia __<span style="font-family: Georgia,serif; font-size: 120%;">- Pseudo-plates

__<span style="font-family: Georgia,serif; font-size: 120%;">Dorsal podia __<span style="font-family: Georgia,serif; font-size: 120%;">- Short rods

__<span style="font-family: Georgia,serif; font-size: 120%;">Tentacles __ || <span style="display: block; font-family: Georgia,serif; font-size: 120%; text-align: center;">**Others** || <span style="display: block; font-family: Georgia,serif; font-size: 120%; text-align: center;"> <span style="display: block; font-family: Georgia,serif; font-size: 120%; text-align: center;">Toxicity || <span style="display: block; font-family: Georgia,serif; font-size: 120%; text-align: center;"> <span style="display: block; font-family: Georgia,serif; font-size: 120%; text-align: center;">Absence of red toxin || <span style="display: block; font-family: Georgia,serif; font-size: 120%; text-align: center;">Releases red toxin (known as holothurin or saponin) when handled or rubbed vigorously || <span style="font-family: Georgia,serif; font-size: 110%;">* Spicules are of primary importance for sea cucumber species identification.
 * <span style="display: block; font-family: Georgia,serif; font-size: 120%; text-align: center;">

= <span style="color: #7823a0; font-family: Georgia,serif; font-size: 130%;">**Potential Value** =

<span style="font-family: Georgia,serif; font-size: 120%;">Isolated organs of //Holothuria leucospilota// have been found to contain significant **antifungal** and **cytotoxic** activity 23]. In the study, extracts from the sea cucumber showed full inhibition of fungal growth at the lowest concentration tested. This has implications on human health as sea cucumbers might in future provide a natural, alternative source of antimicrobial substance to combat antibiotic-resistant pathogens.

<span style="font-family: Georgia,serif; font-size: 120%;">The sea cucumber has also been shown to contain three bioactive compounds (ganglioside molecular species: HLG-1, HLG-2, HLG-3) that were able to stimulate nerve cell growth in rat cells 24]. Another study also identified high **antioxidant** and **antiproliferative** activities of //Holothuria leucospilota// 25]. Aqueous extracts from the sea cucumber has shown high amounts of total phenolics and flavonoids, as well as high antioxidant activity in terms of linoleic acid peroxidation. A study by Ridzwan et al. (2003) has also exhibited that aqueous extracts of //Holothuria leucospilota// has **antinociceptive effects** on mice, which has proven the pain-relieving properties that the sea cucumber possesses as often claimed in folk medicine 26].

= <span style="color: #7823a0; font-family: Georgia,serif; font-size: 130%;">**Conservation Status** =

**<span style="color: #9830cc; font-family: Georgia,serif; font-size: 120%;">Global **
<span style="font-family: Georgia,serif; font-size: 120%;">The status of //Holothuria leucospilota// on a global scale is listed as **Least Concern (LC)** on the IUCN Red List of Threatened species. This is because of its widespread distribution and it is also very common in some parts of its range [17]. Furthermore, it is not intensively fished due to its low commercial value. However, there are concerns that this species may become more popular as other species of higher commercial importance becomes depleted or reduced, such as the //Holothuria scabra// in Thailand 21].

**<span style="color: #9830cc; font-family: Georgia,serif; font-size: 120%;">Singapore **
<span style="font-family: Georgia,serif; font-size: 120%;">The status of //H. leucospilota// is listed as **Vulnerable (VU)** on the Red List of Threatened Animals in Singapore 18]. This is due to continued threats from continued coastal reclamation and developments, which has caused loss of populations of this species in several locations 19]. To prevent this species from going extinct in the wild, sizeable marine protected areas (MPAs) in the Southern Islands of Singapore has to be created 18].

= <span style="color: #7823a0; font-family: Georgia,serif; font-size: 130%;">**Taxonomy & Systematics** =

<span style="color: #9831cc; display: block; font-family: Georgia,serif; font-size: 120%; text-align: left;">**Synonyms 27]**
<span style="font-family: Georgia,serif; font-size: 120%;">//Halodeima dicrona//, 1934 <span style="font-family: Georgia,serif; font-size: 120%;"> //Holothuria (Halodeima) dicorona// (Heding, 1934) <span style="font-family: Georgia,serif; font-size: 120%;"> //Holothuria gelatinosa// Heding, 1939 <span style="font-family: Georgia,serif; font-size: 120%;"> //Holothuria homoea// Clark, 1938 <span style="font-family: Georgia,serif; font-size: 120%;"> //Holothuria infesta// Sluiter, 1901 <span style="font-family: Georgia,serif; font-size: 120%;"> //Holothuria lamperti// Ludwig, 1887 <span style="font-family: Georgia,serif; font-size: 120%;"> //Holothuria oxurropa// Sluiter, 1887 //<span style="font-family: Georgia,serif; font-size: 16px;">Holothuria lagoena //<span style="font-family: Georgia,serif; font-size: 16px;"> Haacke, 1880 <span style="font-family: Georgia,serif; font-size: 120%;">//Holothuria vagabunda// Selenka, 1867

<span style="color: #9831cc; display: block; font-family: Georgia,serif; font-size: 120%; text-align: left;">**Taxonomic classification**
<span style="font-family: Georgia,serif; font-size: 120%;">Phylum Echinodermata <span style="font-family: Georgia,serif; font-size: 120%;"> Class Holothuroidea <span style="font-family: Georgia,serif; font-size: 120%;"> Order Aspidochirotida <span style="font-family: Georgia,serif; font-size: 120%;"> Family Holothuriidae <span style="font-family: Georgia,serif; font-size: 120%;"> Genus //Holothuria// <span style="font-family: Georgia,serif; font-size: 120%;"> Subgenus //Mertensiothuria// <span style="font-family: Georgia,serif; font-size: 120%;"> Species //Holothuria leucospilota//

<span style="color: #9831cc; display: block; font-family: Georgia,serif; font-size: 120%; text-align: left;">**Taxonomic History**
<span style="font-family: Georgia,serif; font-size: 120%;">//Holothuria (Mertensiothuria) leucospilota// was originally //Stichopus (Gymnochirota) leucospilota//, described by Brandt, J.F. in 1835 (Fig. 8) 28].

<span style="color: #9831cc; display: block; font-family: Georgia,serif; font-size: 120%; text-align: left;">**Type information**
<span style="font-family: Georgia,serif; font-size: 120%;">The status and whereabouts of the type material of //H. leucospilota// is undetermined. Although the original type locality was <span style="font-family: Georgia,serif; font-size: 120%; line-height: 1.5;">Ualan, Marshall Islands, attempts to obtain specimens from there were unsuccessful 29]. Thus, the neotype was created from a specimen obtained from the Solomon Islands 30]. The specimen was kept as part of a collection in the Natural History Museum, London 1968.7.3.105–6. Based on article 76.3 of the International Code of Zoological Nomenclature, the Solomon Islands are the type locality of //H. leucospilota// 29].

<span style="font-family: Georgia,serif; font-size: 120%;">This species is also the type species for the subgenus //Mertensiothuria// Deichmann, 1958 29]. //Mertensiothuria// is one of the 20 subgenera recognized under //Holothuria// and to date, six valid species fall under subgenus //Mertensiothuria// 29].

<span style="color: #9831cc; display: block; font-family: Georgia,serif; font-size: 120%; text-align: left;">**Phylogeny**
<span style="font-family: Georgia,serif; font-size: 120%;">Although Rowe (1969) provided a tentative phylogeny based on ossicle similarity which suggested that the genus //Holothuria// was **monophyletic** 31], results presented in Kerr et al. (2005) showed that //Holothuria// was not a single lineage but a **paraphyletic** group that also gave rise to //Pearsonothuria + Bohadschia// and //Labidodemas,// regardless of the tree reconstruction method (Fig.9) 32].



<span style="font-family: Georgia,serif; font-size: 120%;">A study conducted by Wen et al. (2011) aimed at developing a useful and reliable genetic method for the genetic identification of commercial sea cucumber species 33]. A ca. 570bp region of mitochondrial large ribosomal RNA (16S rRNA) gene was selected as the molecular marker. This was because the 16S rRNA gene is well conserved compared to other mitochondrial regions and it evolves faster than nuclear genes, thereby allowing genetic identification of closely related species. The study showed that samples of the same species were grouped in the same clade, allowing the differentiation of all the species included in the present study (Fig.10).



= <span style="color: #7823a0; font-family: Georgia,serif; font-size: 130%;">**Molecular Biology** =

<span style="font-family: Georgia,serif; font-size: 120%;">Two barcode sequences for this species are available from Barcode of Life Data Systems (BOLD) and GenBank. <span style="font-family: Georgia,serif; font-size: 120%;"> The barcode region cytochrome oxidase subunit 1 (COI or COX1) from a member of //H. leucospilota// can be obtained from here.



= <span style="color: #7823a0; font-family: Georgia,serif; font-size: 130%;">**Glossary** =

<span style="font-family: Georgia,serif; font-size: 120%;">**Antinociceptive**: Reducing sensitivity to painful stimuli.

<span style="font-family: Georgia,serif; font-size: 120%;">**Bioturbation**: This is a process that allows reworking of the sediments, increasing sediment turnover rate and promoting oxidation of anoxic layers of sand.

<span style="font-family: Georgia,serif; font-size: 120%;">**Calcareous ring**: This ring serves as an attachment point for muscles operating the oral tentacles and for the anterior ends of other muscles that contract the body longitudinally.


 * <span style="font-family: Georgia,serif; font-size: 16px;">Cloaca **<span style="font-family: Georgia,serif; font-size: 16px;">: Posterior opening that serves as the opening for the intestinal and reproductive tracts of certain animal species.


 * <span style="font-family: Georgia,serif; font-size: 16px;">Cuvierian tubules **<span style="font-family: Georgia,serif; font-size: 16px;">: Organs found in several species of sea cucumbers, all belonging to the family Holothuriidae (order Aspidochirotida). There are two main types of tubules; //Holothuria leucospilota// has smooth tubules that appear as long, sticky, white threads.


 * <span style="font-family: Georgia,serif; font-size: 16px;">Dioecism: **<span style="font-family: Georgia,serif; font-size: 16px;">Individuals of a species are of one of two distinct sexes (either male or female); the more common term to use in the animal kingdom is 'gonochorism'.

<span style="font-family: Georgia,serif; font-size: 120%;">**Epibenthic**: Living on the bottom surface.

<span style="font-family: Georgia,serif; font-size: 120%;">**Monophyletic**: A group composed of a collection of organisms, including the most recent common ancestor of all those organisms and all the descendants of that most recent common ancestor.

<span style="font-family: Georgia,serif; font-size: 120%;">**Neotype**: A new type specimen that is chosen to replace the pre-exisiting type specimen that has been misplaced or destroyed.

<span style="font-family: Georgia,serif; font-size: 120%;">**Papillae**: Fleshy projections of the body wall, usually conical, with a sensory tube foot at its apex.

<span style="font-family: Georgia,serif; font-size: 120%;">**Paraphyletic**: A group composed of a collection of organisms, including the most recent common ancestor of all those organisms but does not include all the descendants of the most recent common ancestor.

<span style="font-family: Georgia,serif; font-size: 120%;">**Rete mirabile**: A fine network of haemal tissue that lies along the gut and functions to disperse nutrients and metabolites.

<span style="font-family: Georgia,serif; font-size: 120%;">**Spicules**: These are also known as ossicles or deposits that function as supporting structures in invertebrates. They are either calcareous or siliceous.

<span style="font-family: Georgia,serif; font-size: 120%;">**Transverse fission**: Splitting of the organism along the short axis of the body into two organisms.

= <span style="color: #7823a0; font-family: Georgia,serif; font-size: 130%;">**Additional Information** =

<span style="display: block; font-family: Georgia,serif; font-size: 120%; text-align: left;">To find out more about the species, do check out some of these interesting **websites**: <span style="display: block; font-family: Georgia,serif; font-size: 120%; text-align: left;">1. WildSingapore <span style="display: block; font-family: Georgia,serif; font-size: 120%; text-align: left;">2. HKmarinelife <span style="display: block; font-family: Georgia,serif; font-size: 120%; text-align: left;">3. For brief information about sea cucumbers as food and medicine <span style="display: block; font-family: Georgia,serif; font-size: 120%; text-align: left;"> <span style="display: block; font-family: Georgia,serif; font-size: 120%; text-align: left;">Check out some of these **videos** too: <span style="display: block; font-family: Georgia,serif; font-size: 120%; text-align: left;">1. For a closer look at the oral tentacles <span style="display: block; font-family: Georgia,serif; font-size: 120%; text-align: left;">2. For information about the black market for sea cucumbers

= <span style="color: #7823a0; font-family: Georgia,serif; font-size: 130%;">**References** =

<span style="font-family: Georgia,serif; font-size: 14px;">[1] Clark, H. L., 1946. //<span style="font-family: Georgia,serif; font-size: 14px;">The echinoderm fauna of Australia //<span style="font-family: Georgia,serif; font-size: 14px;">. Carnegie Institution of Washington, Washington, D.C, pp. 383­–461.

[2] Cannon, L. R. G. & H. Silver, 1986. //<span style="font-family: Georgia,serif; font-size: 14px;">Sea Cucumbers of Northern Australia //<span style="font-family: Georgia,serif; font-size: 14px;">. Queensland Museum, South Brisbane, Australia, pp. 1–25.

[3] Schneider, K., J. Silverman, E. Woolsey, H. Eriksson, M. Byrne & K. Caldeira, 2011. Potential influence of sea cucumbers on coral reef CaCO3 budget: A case study at One Tree Reef. //<span style="font-family: Georgia,serif; font-size: 14px;">Journal of Geophysical Research //<span style="font-family: Georgia,serif; font-size: 14px;">, 116(G4): 2005–2012.

[4] Hsieh, V., 2012. //<span style="font-family: Georgia,serif; font-size: 14px;">Monitoring organ regeneration of sea cucumber Holothuria leucospilota after evisceration //<span style="font-family: Georgia,serif; font-size: 14px;">. Student Research Papers, Fall 2012. University of California, Berkeley, 11 pp.

[5] Ong Che, R. G., 1990. Aspects of the feeding biology of Holothuria leucospilota Brandt (Echinodermata: Holothuroidea) in Hong Kong. //<span style="font-family: Georgia,serif; font-size: 14px;">Asian Marine Biology //<span style="font-family: Georgia,serif; font-size: 14px;">, 7:133–146.

[6] Wilkie, I. C., 2001. Autotomy as a prelude to regeneration in echinoderms. //<span style="font-family: Georgia,serif; font-size: 14px;">Microscopy Research and Technique //<span style="font-family: Georgia,serif; font-size: 14px;">, 55(6): 369-396.

[7] Dolmatov, I. Y., N. A. Khang & Y. O. Kamenev, 2014. Asexual reproduction, evisceration, and regeneration in holothurians (Holothuroidea) from Nha Trang Bay of the South China Sea. //Russian Journal of Marine Biology//, 38(3): 243­–252.

[8] Purwati, P., 2001. //<span style="font-family: Georgia,serif; font-size: 14px;">Reproduction in Holothuria leucospilota in the tropical waters of Darwin, NT, Australia //<span style="font-family: Georgia,serif; font-size: 14px;">. MSc Thesis. Northern Territory University, Australia, 147 pp.

[9] Taquet, C., F. Setiawan, N. Yasuda, Suharsono & K. Nadaoka, 2011. First observation of a large group of //Holothuria leucospilota// sea cucumber juveniles at a nursery in Manado (north Sulawesi, Indonesia). //SPC Beche-de-mer Information Bulletin//, 31:30–34.

[10] Purwati, P. & J. T. Luong-van, 2003. Sexual reproduction in a fissiparous holothurian species, Holothuria leucospilota Clark 1920 (Echinodermata: Holothuroidea). //SPC Beche-de-mer Information Bulletin//, 18:33–38.

[11] Conand, C., 1998. //Holothurians//. In: K. E. Carpenter & V. H. Niem (eds.) FAO species identification guide for fishery purposes. The living marine resources of the Western Central Pacific. Volume 2. Cephalopods, crustaceans, holothurians and sharks. Food and Agriculture Organization of the United Nations, Rome, pp. 1158–1184.  [12] Chao, S. M., C. P. Chen & P. S. Alexander, 1995. Reproductive cycles of tropical sea cucumbers (Echinodermata: Holothuroidea) in southern Taiwan. //<span style="font-family: Georgia,serif; font-size: 14px;">Marine Biology //<span style="font-family: Georgia,serif; font-size: 14px;">, 122: 289–295.

[13] Miyazaki, S., T. Ichiba, J. D. Reimer & J. Tanaka, 2014. Chemoattraction of the pearlfish //<span style="font-family: Georgia,serif; font-size: 14px;">Encheliophis vermicularis //<span style="font-family: Georgia,serif; font-size: 14px;"> to the sea cucumber //<span style="font-family: Georgia,serif; font-size: 14px;">Holothuria leucospilota //<span style="font-family: Georgia,serif; font-size: 14px;">. //<span style="font-family: Georgia,serif; font-size: 14px;">Chemoecology //<span style="font-family: Georgia,serif; font-size: 14px;">, 24(3): 121–126.

[14] Smith, C. L., J. C. Tyler & M. N. Feinberg, 1981. Population ecology and biology of the pearlfish //<span style="font-family: Georgia,serif; font-size: 14px;">(Carapus bermudensis) //<span style="font-family: Georgia,serif; font-size: 14px;"> in the lagoon at Bimini, Bahamas. //<span style="font-family: Georgia,serif; font-size: 14px;">Bulletin of Marine Science //<span style="font-family: Georgia,serif; font-size: 14px;">, 31: 876–902. 

[15] Murdy, E. O. & M. E. Cowan, 1980. Observations on the behaviour and symbiotic relationship of the pearlfish //<span style="font-family: Georgia,serif; font-size: 14px;">Encheliophis vermicularis //<span style="font-family: Georgia,serif; font-size: 14px;"> (Osteichthys: Carapidae). //<span style="font-family: Georgia,serif; font-size: 14px;">Kalikasan //<span style="font-family: Georgia,serif; font-size: 14px;">, 9(2): 309–312.

[16] Woodland, D., 2005. //<span style="font-family: Georgia,serif; font-size: 14px;">Parasitic marine fishes //<span style="font-family: Georgia,serif; font-size: 14px;">. In: K. Rohde (ed.) Marine Parasitology, Collingwood, Victoria, pp. 250–258.

[17] Conand, C., S. Purcell & R. Gamboa, 2013. Holothuria leucospilota. The IUCN Red List of Threatened Species. Version 2014.2. [] (Assessed 20 October 2014). 

[18] Lane, D. J. W., 2008. //<span style="font-family: Georgia,serif; font-size: 14px;">Echinodermata //<span style="font-family: Georgia,serif; font-size: 14px;">. In: G. W. H. Davison, P. K. L. Ng & H. H. Chew (eds.) The Singapore Red Data Book: Threatened plants & animals of Singapore. The Nature Society, Singapore, p. 138.

[19] Lane, D. J. W. & D. Vandenspiegel, 2003. //<span style="font-family: Georgia,serif; font-size: 14px;">A guide to sea stars and other echinoderms of Singapore //<span style="font-family: Georgia,serif; font-size: 14px;">. Singapore Science Centre, Singapore, p. 146.

[20] James, D. B., 1995. Taxonomic Studies on the species of //<span style="font-family: Georgia,serif; font-size: 14px;">Holothuria //<span style="font-family: Georgia,serif; font-size: 14px;"> Linnaeus, 1767 from the seas around India. //<span style="font-family: Georgia,serif; font-size: 14px;">Journal of the Bombay Natural History Society //<span style="font-family: Georgia,serif; font-size: 14px;">, 92(2): 190–204.[[#James 1995][7] Conand, C., S. Purcell & R. Gamboa, 2013. //<span style="font-family: Georgia,serif; font-size: 14px;">Holothuria leucospilota //<span style="font-family: Georgia,serif; font-size: 14px;">. The IUCN Red List of Threatened Species. Version 2014.2. [] (Assessed 20 October 2014).

[21] Choo, P. S, 2008. //<span style="font-family: Georgia,serif; font-size: 14px;">Population status, fisheries and trade of sea cucumbers in Asia //<span style="font-family: Georgia,serif; font-size: 14px;">. In: V. Toral-Granda, A. Lovatelli, and M. Vasconcellos (eds.) Sea cucumbers. A global review of fisheries and trade. FAO Fisheries and Aquaculture Technical Paper, Rome, pp. 81–118.

[22] Kerr, A. M., 2000. //<span style="font-family: Georgia,serif; font-size: 14px; line-height: 1.5;">Holothuroidea. Sea cucumbers //<span style="font-family: Georgia,serif; font-size: 14px;">. The Tree of Life Web Project. [] (Assessed 1 November 2014).

[23] Mohammadizadeh, F., M. Ehsanpor, M. Afkhami, A. Mokhlesi, A. Khazaali & S. Montazeri, 2013. Antibacterial, antifungal and cytotoxic effects of a sea cucumber //Holothuria leucospilota//, from the north coast of the Persian Gulf. //Journal of the Marine Biological Association of the United Kingdom//, 93(5): 1401­–1405.

[24] Yamada, K., R. Matsubara, M. Kaneko, T. Miyamoto & R. Higuchi, 2001. Constituents of Holothuroidea. 10. 1) Isolation and structure of a biologically active ganglioside molecular species from the sea cucumber Holothuria leucospilota. //<span style="font-family: Georgia,serif; font-size: 14px;">Chemical and Pharmaceutical Bulletin //<span style="font-family: Georgia,serif; font-size: 14px;">, 49(4): 447–452.

<span style="font-family: Georgia,serif; font-size: 110%;"> [25] Althuibat, O. Y., R. B. Hashim, M. Taher, J. M. Daud, M. A. Ikeda & B. I. Zali, 2009. In vitro antioxidant and antiproliferative activities of three Malaysian sea cucumber species. //European Journal of Scientific Research//, 37(3): 376–387.

<span style="font-family: Georgia,serif; font-size: 14px;"> [26] Ridzwan, B. H., T. C. Leong & S. Z. Idid, 2003. The antinociceptive effects of water extracts from sea cucumbers //Holothuria leucospilota// Brandt, //Bohadschia marmorata vitiensis// Jaeger and coelomic fluid from //Sticophus hermanii//. //Pakistan Journal of Biological Sciences//, 6(24): 2068–2072.

[27] Paulay, G., 2014. //<span style="font-family: Georgia,serif; font-size: 14px;">Holothuria (Mertensiothuria) leucospilota (Brandt, 1835) //<span style="font-family: Georgia,serif; font-size: 14px;">. @http://www.marinespecies.org/aphia.php?p=taxdetails&id=210881 (Assessed 21 October 2014).

<span style="font-family: Georgia,serif; font-size: 110%;">[28] Brandt, J. F., 1835. //Prodromus descriptionis animalium ab H. Mertensio observatorum : fascic. I. Polypos, Acalephas Discophoras et Siphonophoras, nec non Echinodermata continens//. Sumptibus Academiae, p.251.

<span style="font-family: Georgia,serif; font-size: 14px;">[29] Samyn, Y. & C. Massin, 2003. The holothurian subgenus //Mertensiothuria// (Aspidochirotida: Holothuriidae) revisited. //Journal of Natural History//, 37(20): 2487–2519.

[30] Samyn, Y., 2003. Shallow-water Holothuroidea (Echinodermata) from Kenya and Pemba Island, Tanzania. //Studies in Afrotropical Zoology//, 292: 9–47.

[31] Rowe, F., 1969. A review of the family Holothuriidae (Holothurioidea: Aspidochirotida). //Bulletin of the British Museum (Natural History)//, 18:7–170.

<span style="font-family: Georgia,serif; font-size: 110%;"> [32] Kerr, A. M., D. A. Janies, R. M. Clouse, Y. Samyn, J. Kuszak, & J. Kim, 2005. Molecular phylogeny of coral-reef sea cucumbers (Holothuriidae: Aspidochirota) based on 16S Mitochondrial ribosomal DNA sequence. //Marine Biotechnolog//y, 7: 53–60.

<span style="font-family: Georgia,serif; font-size: 14px;">[33] Wen, J., C. Hu, L. Zhang & S. Fan, 2011. Genetic identification of global commercial sea cucumber species on the basis of mitochondrial DNA sequences. //Food Control//, 22(1): 72–77. 

<span style="font-family: Georgia,serif; font-size: 110%;">[34] Ratnasingham, S. & P. D. N. Hebert, 2014. //Barcode data: Holothuria leucospilota//. [] (Assessed 24 October 2014).