Umbonium+vestiarium

toc Button snails are commonly encountered at low tide level on sandy beach. These small, button-like shells are often half-covered with sand, and many more can be found under the wet sand. The colourful shells make them particularly attractive; nevertheless, the maintenance and development of its polymorphic shells is not investigated in detail yet. This filter-feeding snail is vulnerable to anthropogenic activities, especially habitat destruction, and has been listed as 'vulnerable' on Singapore Red Data Book 2008.
 * Button snail ** //Umbonium vestiarium// (Linnaeus, 1758)
 * [[image:button snails sand.jpg width="438" height="349" link="https://www.flickr.com/photos/wildsingapore/2791785268/in/photolist-cYRNRy-cYRNLS-cYRNfU-cYRMXu-cYRMy1-cYRMdq-cYRLX9-cYRLxy-cYRLbU-cYRL2S-cYRKKC-cYRKDY-cYRKvf-aPGFTZ-aJmpDv-aJmpA2-aj1yfU-aj1ydJ-aj1vmL-8Uir7z-aj1ybE-aiXLgP-aj1y7b-aiXLd4-aiXLb8-aj1voh-aiXCVk-9HtgVi-9aa3E7-8TxmaR-8PpDtD-8Psvhy-8C897z-8Cbfho-8eSJXV-8eW2tq-8eW2nS-8eSEX4-7LNm9x-7LSje9-7LNm4V-7j5cjq-6qGo1k-5fGCuL-54fgi8-54fgdv-VaNRC-KZjge-Gq6vU-4TBfKU"]][[image:live button snail 3 (ria tan 2011).jpg width="431" height="350" link="https://www.flickr.com/photos/wildsingapore/7863366330/in/photolist-cYRNRy-cYRNLS-cYRNfU-cYRMXu-cYRMy1-cYRMdq-cYRLX9-cYRLxy-cYRLbU-cYRL2S-cYRKKC-cYRKDY-cYRKvf-aPGFTZ-aJmpDv-aJmpA2-aj1yfU-aj1ydJ-aj1vmL-8Uir7z-aj1ybE-aiXLgP-aj1y7b-aiXLd4-aiXLb8-aj1voh-aiXCVk-9HtgVi-9aa3E7-8TxmaR-8PpDtD-8Psvhy-8C897z-8Cbfho-8eSJXV-8eW2tq-8eW2nS-8eSEX4-7LNm9x-7LSje9-7LNm4V-7j5cjq-6qGo1k-5fGCuL-54fgi8-54fgdv-VaNRC-KZjge-Gq6vU-4TBfKU"]] ||
 * Figure 1: Button snails found on sandy beach (left) and a close-up of the snail (right). Photo: © 2008 & 2012 Ria Tan (CC BY-NC-ND 2.0) ||

=1. Physical appearance = Button snail has round and glossy shell with various patterns and colours (Figure 2). Its average shell width is 1 cm, with maximum of 1.5 cm 1] . More information about its identifying features can be found on 5(ii) Diagnostic features. Empty shell may be occupied by hermit crab, so do take a closer look to find out whether it is button snail or hermit crab. The main distinguishing feature is that button snail has soft body while hermit crab has claws and legs like crabs (Figure 3 and 4). [|Polymorphism], which refers to having two or more different sizes, shapes, colours, patterns, etc., within a population 2] , is a characteristic feature of many gastropod shells. Button snail exhibits particularly high polymorphism: 11 colour patterns were recorded in Kalbadevi beach in India 3]  and up to 96 distinct morphs in Singapore 30] . However, the development and maintenance of the polymorphism is still a mystery. Both genetic and environmental factors are likely to play a role, but more studies need to be conducted to investigate this. One possible mechanism is [|apostatic selection] through differential predation rates on morphs <span style="font-family: Arial,Helvetica,sans-serif; font-size: 10pt; vertical-align: super;">4] <span style="font-family: Arial,Helvetica,sans-serif; font-size: 11pt;">. <span style="font-family: Arial,Helvetica,sans-serif; font-size: 15px;">However, this is unlikely given that the main predators of button snail, such as moon snails and sea stars, hunt primarily by smell and not visual. Another possible mechanism is heat management —<span style="font-family: Arial,Helvetica,sans-serif; font-size: 15px;">dark-coloured morphs may be at disadvantage because they get heated up faster and more prone to desiccation <span style="font-family: Arial,Helvetica,sans-serif; font-size: 10pt; vertical-align: super;">5] <span style="font-family: Arial,Helvetica,sans-serif; font-size: 15px;">, especially in tropics where solar radiation and temperatures are high. Indeed, darker morphs were observed to be lower in number <span style="font-family: Arial,Helvetica,sans-serif; font-size: 10pt; vertical-align: super;">3,30] <span style="font-family: Arial,Helvetica,sans-serif; font-size: 15px;">.
 * [[image:button snail morphs.png width="535" height="225"]] ||
 * <span style="font-family: Arial,Helvetica,sans-serif; font-size: 10pt;">Figure 2: Various shell patterns of button snail. Photo: © 2015 Jenny ||
 * [[image:button snail 2012.jpg width="432" height="327" link="https://www.flickr.com/photos/wildsingapore/7863360812/in/photolist-cYRNRy-cYRNLS-cYRNfU-cYRMXu-cYRMy1-cYRMdq-cYRLX9-cYRLxy-cYRLbU-cYRL2S-cYRKKC-cYRKDY-cYRKvf-aPGFTZ-aJmpDv-aJmpA2-aj1yfU-aj1ydJ-aj1vmL-8Uir7z-aj1ybE-aiXLgP-aj1y7b-aiXLd4-aiXLb8-aj1voh-aiXCVk-9HtgVi-9aa3E7-8TxmaR-8PpDtD-8Psvhy-8C897z-8Cbfho-8eSJXV-8eW2tq-8eW2nS-8eSEX4-7LNm9x-7LSje9-7LNm4V-7j5cjq-6qGo1k-5fGCuL-54fgi8-54fgdv-VaNRC-KZjge-Gq6vU-4TBfKU"]] || [[image:hermit crab 2005.jpg width="446" height="333" align="center" link="https://www.flickr.com/photos/wildsingapore/2553090162/in/photolist-cYRNRy-cYRNLS-cYRNfU-cYRMXu-cYRMy1-cYRMdq-cYRLX9-cYRLxy-cYRLbU-cYRL2S-cYRKKC-cYRKDY-cYRKvf-aPGFTZ-aJmpDv-aJmpA2-aj1yfU-aj1ydJ-aj1vmL-8Uir7z-aj1ybE-aiXLgP-aj1y7b-aiXLd4-aiXLb8-aj1voh-aiXCVk-9HtgVi-9aa3E7-8TxmaR-8PpDtD-8Psvhy-8C897z-8Cbfho-8eSJXV-8eW2tq-8eW2nS-8eSEX4-7LNm9x-7LSje9-7LNm4V-7j5cjq-6qGo1k-5fGCuL-54fgi8-54fgdv-VaNRC-KZjge-Gq6vU-4TBfKU"]] ||
 * <span style="font-family: Arial,Helvetica,sans-serif; font-size: 10pt;">Figure 3: Button snail. Photo © 2012 Ria Tan ( <span style="font-family: Arial,Helvetica,sans-serif;">CC BY-NC-ND 2.0) || <span style="font-family: Arial,Helvetica,sans-serif; font-size: 10pt;">Figure 4: Hermit crab living in an empty button snail. Photo: © 2005 Ria Tan <span style="font-family: Arial,Helvetica,sans-serif;">(CC BY-NC-ND 2.0) ||

=<span style="color: #0157fc; font-family: Arial,Helvetica,sans-serif; font-size: 15pt;">2. Distribution =

**<span style="font-family: Arial,Helvetica,sans-serif; font-size: 13pt;">(i) **<span style="font-family: Arial,Helvetica,sans-serif; font-size: 13pt; font-variant: small-caps;">Habitat
<span style="font-family: Arial,Helvetica,sans-serif; font-size: 10pt;"><span style="font-family: Arial,Helvetica,sans-serif; font-size: 11pt;">Button snail inhabits surface layers of marine sands in shallow water and also low-shore mud flats. It prefers sand of medium grade and avoids finer [|sand grains] or muddy sand <span style="font-family: Arial,Helvetica,sans-serif; font-size: 10pt; vertical-align: super;">6, <span style="font-family: Arial,Helvetica,sans-serif; font-size: 10pt; vertical-align: super;">7] <span style="font-family: Arial,Helvetica,sans-serif; font-size: 15px;">. <span style="font-family: Arial,Helvetica,sans-serif; font-size: 10pt;"> It has greatest abundance on undisturbed beaches with medium wave energy [ <span style="font-family: Arial,Helvetica,sans-serif; font-size: 10pt; vertical-align: super;">3] <span style="font-family: Arial,Helvetica,sans-serif; font-size: 15px;">.

<span style="font-family: Arial,Helvetica,sans-serif; font-size: 13pt;">(ii) <span style="font-family: Arial,Helvetica,sans-serif; font-size: 13pt; font-variant: small-caps;">Worldwide
<span style="font-family: Arial,Helvetica,sans-serif; font-size: 11pt;">It is commonly found in Indo-Pacific: East Africa, India, Southeast Asia, and Australia <span style="font-family: Arial,Helvetica,sans-serif; font-size: 15px;">(Figure 5) <span style="font-family: Arial,Helvetica,sans-serif; font-size: 10pt; vertical-align: super;">1] <span style="font-family: Arial,Helvetica,sans-serif; font-size: 15px;">.

<span style="font-family: Arial,Helvetica,sans-serif; font-size: 13pt;">(iii) <span style="font-family: Arial,Helvetica,sans-serif; font-size: 13pt; font-variant: small-caps;">Singapore
<span style="font-family: Arial,Helvetica,sans-serif; font-size: 10pt;"><span style="font-family: Arial,Helvetica,sans-serif; font-size: 11pt;">It is abundant in the sandy shores in Singapore (Figure 5; e.g. Changi, Chek Jawa, Cyrene Reef, East Coast Park, and Tanah Merah) <span style="font-family: Arial,Helvetica,sans-serif; font-size: 10pt; vertical-align: super;">[ <span style="font-family: Arial,Helvetica,sans-serif; font-size: 10pt; vertical-align: super;">8] <span style="font-family: Arial,Helvetica,sans-serif; font-size: 15px;">. <span style="font-family: Arial,Helvetica,sans-serif; font-size: 11pt;">Empty shells are often washed ashore on mid and high level tide.
 * [[image:global distribution.png]] || [[image:sg distribution.png]] ||
 * <span style="font-family: Arial,Helvetica,sans-serif; font-size: 10pt;">Figure 5: Global distribution of button snail. Source: Global Biodiversity Information Facility ( <span style="font-family: Arial,Helvetica,sans-serif;">CC BY 3.0) <span style="font-family: Arial,Helvetica,sans-serif; font-size: 10pt; vertical-align: super;">9] || <span style="font-family: Arial,Helvetica,sans-serif; font-size: 10pt;">Figure 6: Distribution of button snail in Singapore. Base map from Global Biodiversity Information Facility (CC BY 3.0) <span style="font-family: Arial,Helvetica,sans-serif; font-size: 10pt; vertical-align: super;">9] <span style="font-family: Arial,Helvetica,sans-serif; font-size: 10pt;">; reference points adapted from Lee Kong Chian Natural History Museum <span style="font-family: Arial,Helvetica,sans-serif; font-size: 10pt; vertical-align: super;">8] ||

=<span style="color: #0157fc; font-family: Arial,Helvetica,sans-serif; font-size: 15pt;">3. Biology =

**<span style="font-family: Arial,Helvetica,sans-serif; font-size: 13pt;">(i) **<span style="font-family: Arial,Helvetica,sans-serif; font-size: 13pt; font-variant: small-caps;">Behaviour
<span style="font-family: Arial,Helvetica,sans-serif; font-size: 10pt;"><span style="font-family: Arial,Helvetica,sans-serif; font-size: 11pt;">As the tide recedes, button snail buries itself and closes the aperture of its shell with operculum before the surface of the sand dries; it resumes its activity when the tide rises <span style="font-family: Arial,Helvetica,sans-serif; font-size: 10pt; vertical-align: super;">[ <span style="font-family: Arial,Helvetica,sans-serif; font-size: 10pt; vertical-align: super;">10]. <span style="font-family: Arial,Helvetica,sans-serif; font-size: 11pt;">As it creeps, a path marking is made by the edge of the outer [|lip] of the shell and the foot <span style="font-family: Arial,Helvetica,sans-serif; font-size: 10pt; vertical-align: super;">10] <span style="font-family: Arial,Helvetica,sans-serif; font-size: 11pt;">, forming a trail (Figure 7 and 8). <span style="font-family: Arial,Helvetica,sans-serif; font-size: 15px;">Owing to its low [|spire] and smooth surface, button snail encounters little resistance to burrow <span style="font-family: Arial,Helvetica,sans-serif; font-size: 10pt; vertical-align: super;">10] .<span style="font-family: Arial,Helvetica,sans-serif; font-size: 11pt;"> The front end of the foot, which is split into two parts, is curved, allowing it to carry out ploughshare-like action <span style="font-family: Arial,Helvetica,sans-serif; font-size: 10pt; vertical-align: super;">10,11] <span style="font-family: Arial,Helvetica,sans-serif; font-size: 11pt;">(Figure 7). The modification of the foot facilitates its movement in soft substrata, but traversing across hard substratum is difficult <span style="font-family: Arial,Helvetica,sans-serif; font-size: 10pt; vertical-align: super;">10] <span style="font-family: Arial,Helvetica,sans-serif; font-size: 11pt;">. This may explain why button snail is found on sandy shores, and not rocky ones. To escape predators, button snail may perform a series of rolling movements by twisting their foot side to side <span style="font-family: Arial,Helvetica,sans-serif; font-size: 10pt; vertical-align: super;">12] <span style="font-family: Arial,Helvetica,sans-serif; font-size: 11pt;">. High density of button snail, up to 77,700 snails per m <span style="font-family: Arial,Helvetica,sans-serif; font-size: 10pt; vertical-align: super;">210] <span style="font-family: Arial,Helvetica,sans-serif; font-size: 11pt;">, may be found in one spot (Figure 9). <span style="font-family: Arial,Helvetica,sans-serif; font-size: 11pt;">By actively fixing mucus from its expanded foot with sediment, button snail can aggregate and gain greater resistance from being washed away in high energy shores, where optimal feeding and reproduction can be achieved <span style="font-family: Arial,Helvetica,sans-serif; font-size: 10pt; vertical-align: super;">10] <span style="font-family: Arial,Helvetica,sans-serif; font-size: 11pt;">.
 * [[image:Untitled.png width="602" height="287" align="center" link="https://www.flickr.com/photos/wildsingapore/7863365814/in/photolist-cYRNGE-cYRNfU-cYRMXu-cYRLxy-cYRKDY-cYRKvf-zKf53b-daxugB-cYRP6y-cYRP1N-cYRNXf-cYRNRy-cYRNLS-cYRMy1-cYRMdq-cYRLX9-cYRLbU-cYRL2S-cYRKKC-aPGFTZ-aJmpDv-aJmpA2-aj1yfU-aj1ydJ-aiXLgP-aj1y7b-aj1voh-aiXCVk-8TxmaR-8Psvhy-8C897z-8eSEX4-7LSje9-7j5cjq-6qGo1k-aj1ybE-aiXLd4-aiXLb8-aj1vmL-9HtgVi-9aa3E7-8Uir7z-8PpDtD-8Cbfho-8eSJXV-8eW2tq-8eW2nS-7LNm9x-7LNm4V-5fGCuL"]] ||
 * <span style="font-family: Arial,Helvetica,sans-serif; font-size: 10pt;">Figure 7: Labels of selected anatomy. Photo: © 2012 Ria Tan ( <span style="font-family: Arial,Helvetica,sans-serif;">CC BY-NC-ND 2.0) <span style="font-family: Arial,Helvetica,sans-serif; font-size: 10pt;">, labelled and edited by Jenny. Insert photo: © 2015 Jenny ||


 * [[image:button snail trail mark (ria tan 2011).jpg width="400" height="299" align="center" link="https://www.flickr.com/photos/wildsingapore/6110471107/in/photolist-cYRNRy-cYRNLS-cYRNfU-cYRMXu-cYRMy1-cYRMdq-cYRLX9-cYRLxy-cYRLbU-cYRL2S-cYRKKC-cYRKDY-cYRKvf-aPGFTZ-aJmpDv-aJmpA2-aj1yfU-aj1ydJ-aj1vmL-8Uir7z-aj1ybE-aiXLgP-aj1y7b-aiXLd4-aiXLb8-aj1voh-aiXCVk-9HtgVi-9aa3E7-8TxmaR-8PpDtD-8Psvhy-8C897z-8Cbfho-8eSJXV-8eW2tq-8eW2nS-8eSEX4-7LNm9x-7LSje9-7LNm4V-7j5cjq-6qGo1k-5fGCuL-54fgi8-54fgdv-VaNRC-KZjge-Gq6vU-4TBfKU"]] || [[image:large button snails floating.jpg width="407" height="303" align="center" link="https://www.flickr.com/photos/wildsingapore/2662159313/in/photolist-zKf53b-daxugB-cYRP6y-cYRP1N-cYRNXf-cYRNRy-cYRNLS-cYRMy1-cYRMdq-cYRLX9-cYRLbU-cYRL2S-cYRKKC-aPGFTZ-aJmpDv-aJmpA2-aj1yfU-aj1ydJ-aiXLgP-aj1y7b-aj1voh-aiXCVk-8TxmaR-8Psvhy-8C897z-8eSEX4-7LSje9-7j5cjq-6qGo1k-aj1ybE-aiXLd4-aiXLb8-aj1vmL-9HtgVi-9aa3E7-8Uir7z-8PpDtD-8Cbfho-8eSJXV-8eW2tq-8eW2nS-7LNm9x-7LNm4V-5fGCuL-54fgi8-54fgdv-Gq6vU-4TBfKU-VaNRC-KZjge"]] ||
 * <span style="font-family: Arial,Helvetica,sans-serif; font-size: 10pt;">Figure 8: Path marking made as button snail creeps on sand. Photo: © 2011 Ria Tan ( <span style="font-family: Arial,Helvetica,sans-serif;">CC BY-NC-ND 2.0) |||| <span style="font-family: Arial,Helvetica,sans-serif; font-size: 10pt;">Figure 9: Aggregation of floating button snail. Photo: © 2008 Ria Tan ( <span style="font-family: Arial,Helvetica,sans-serif;">CC BY-NC-ND 2.0) ||

<span style="font-family: Arial,Helvetica,sans-serif; font-size: 13pt;">(ii) <span style="font-family: Arial,Helvetica,sans-serif; font-size: 13pt; font-variant: small-caps;">Feeding
<span style="font-family: Arial,Helvetica,sans-serif; font-size: 11pt;">Button snail is a suspension feeder. It belongs to //genus// Umbonium, the only filter-feeding gastropod group with inhalant and exhalant siphons <span style="font-family: Arial,Helvetica,sans-serif; font-size: 10pt; vertical-align: super;">10] <span style="font-family: Arial,Helvetica,sans-serif; font-size: 11pt;">. It picks up food as it glides over the sand surface or if it is buried, it will extend its two siphons to filter feed instead, as shown in Figure 10 <span style="font-family: Arial,Helvetica,sans-serif; font-size: 10pt; vertical-align: super;">10] //<span style="font-family: Arial,Helvetica,sans-serif; font-size: 11pt;">. //
 * [[image:half buried filtering.png width="800" height="355" link="https://www.flickr.com/photos/wildsingapore/7863355060/in/photolist-cYRNLS-cYRNGE-cYRNfU-cYRMXu-cYRMy1-cYRMdq-cYRLX9-cYRLxy-cYRLbU-cYRL2S-cYRKKC-cYRKDY-cYRKvf-aPGFTZ-aJmpDv-aJmpA2-aj1yfU-aj1ydJ-aj1ybE-aiXLgP-aj1y7b-aiXLd4-aiXLb8-aj1voh-aj1vmL-aiXCVk-9HtgVi-9aa3E7-8Uir7z-8TxmaR-8PpDtD-8Psvhy-8C897z-8Cbfho-8eSJXV-8eW2tq-8eW2nS-8eSEX4-7LNm9x-7LSje9-7LNm4V-7j5cjq-6qGo1k-5fGCuL-54fgi8-54fgdv-4TBfKU-VaNRC-KZjge-Gq6vU"]] ||
 * Figure 10: Button snail buried in sand in feeding position. Left photo: © 2012 Ria Tan (CC BY-NC-ND 2.0), labelled by Jenny. Right illustration by Jenny, with reference to 13] ||

<span style="font-family: Arial,Helvetica,sans-serif; font-size: 13pt;">(iii) <span style="font-family: Arial,Helvetica,sans-serif; font-size: 13pt; font-variant: small-caps;">Predators
<span style="font-family: Arial,Helvetica,sans-serif; font-size: 11pt;">Button snail is preyed mainly by moon snails (Naticidae) and starfish (Astropectinidae), and occasionally by a few other marine invertebrates and fish (Figure 11) <span style="font-family: Arial,Helvetica,sans-serif; font-size: 10pt; vertical-align: super;">14,15] <span style="font-family: Arial,Helvetica,sans-serif; font-size: 11pt;">.
 * [[image:ball moon snail preying button snail (ria tan 2011).jpg width="461" height="341" link="https://www.flickr.com/photos/wildsingapore/6111006688/in/photolist-aj1voh-aj1vmL-81tZGD-8rSSEy-8Psvhy-daxugB-GRpcR-8kVLtU-GRnuw-GRpqF-8a2Av5-a3WLDa-86BPUF-81xaJN-6fdEbt-6fdE46-7BFqLD-7UUu6J-8kVLLw-8LDuaP-8kSeWX-8kVq1N-fVW2YW-fVX2Hx-dqHgax-86BRJk-833dKb-898NcR-8rQ9B6-8rPNp6-8kVpHb-8kVM3y-833edd-86F3cE-86BP14-86BQkZ-7VmWaN-7VmVSw-8vgSf1-aHez5X-aAjT6D-aAjTxk-5ttuS7-aAnBJU-5tp6PM-wYbtg7-WRnNR-5tp73n-5tp6VH-5tp7d4"]][[image:haddon carpet preying button snail (ria tan 2005).jpg width="456" height="339" link="https://www.flickr.com/photos/wildsingapore/8527836174/in/photolist-dZzoAb-daxugB-cYRP6y-cYRP1N-cYRNXf-cYRNRy-cYRNLS-cYRNGE-cYRNfU-cYRMXu-cYRMy1-cYRMdq-cYRLX9-cYRLxy-cYRLbU-cYRL2S-cYRKKC-cYRKDY-cYRKvf-aPGFTZ-aJmpDv-aJmpA2-aj1yfU-aj1ydJ-aj1ybE-aiXLgP-aj1y7b-aiXLd4-aiXLb8-aj1voh-aj1vmL-aiXCVk-9HtgVi-9aa3E7-8Uir7z-8TxmaR-8PpDtD-8Psvhy-8C897z-8Cbfho-8eSJXV-8eW2tq-8eW2nS-8eSEX4-7LNm9x-7LSje9-7LNm4V-7j5cjq-6qGo1k-5fGCuL"]] ||
 * Figure 11: Button snails being preyed by moon snail (left) and Haddon's carpet anemone (right). Photo: © 2011 & 2005 Ria Tan (CC BY-NC-ND 2.0) ||

<span style="font-family: Arial,Helvetica,sans-serif; font-size: 13pt;">(iv) <span style="font-family: Arial,Helvetica,sans-serif; font-size: 13pt; font-variant: small-caps;">Reproduction & Lifespan
<span style="font-family: Arial,Helvetica,sans-serif; font-size: 11pt;">Button snail has separate sexes (i.e. dioious). Similar to other trochacaeans in the family, button snail is a broadcast spawner and carries out external fertilization because it lacks the accessory reproductive organs for internal fertilisation <span style="font-family: Arial,Helvetica,sans-serif; font-size: 10pt;"><span style="font-family: Arial,Helvetica,sans-serif; font-size: 10pt; vertical-align: super;">15] <span style="font-family: Arial,Helvetica,sans-serif; font-size: 11pt;">. Most favourable condition for spawning occurs during the period of weakest neap tides with high water level during mid-day because there is minimum change in water level, providing permanent cover <span style="font-family: Arial,Helvetica,sans-serif; font-size: 10pt; vertical-align: super;">15,16] <span style="font-family: Arial,Helvetica,sans-serif; font-size: 11pt;">. Based on a study done for a population in Peninsular Malaysia, the greatest amount of spawning was recorded between March and August <span style="font-family: Arial,Helvetica,sans-serif; font-size: 10pt; vertical-align: super;">17] <span style="font-family: Arial,Helvetica,sans-serif; font-size: 11pt;">. Mid-day spawning is advantageous because it allows <span style="font-family: Arial,Helvetica,sans-serif; font-size: 15px;">the [|trochophore] and early [|veligers] larvae, which are negatively gravitaxis and will orient themselves against gravity and move upwards, to have light-enhanced upward swimming. This promotes faster growth <span style="font-family: Arial,Helvetica,sans-serif; font-size: 10pt;"> before the night sets, before the development of positively gravitaxis veligers 15]. As a result of weak dispersal, the offspring is likely to settle on the same shore. However, weak dispersal is favourable to button snail. Given that the juvenile live and grow for one year before breeding and then die the following mid-year 10,15], there will be little competition between established parents and settling juveniles 15]. <span style="font-family: Arial,Helvetica,sans-serif; font-size: 11pt;">To compensate for its short life, button snail also has high reproduction output <span style="font-family: Arial,Helvetica,sans-serif; font-size: 10pt; vertical-align: super;">17] <span style="font-family: Arial,Helvetica,sans-serif; font-size: 11pt;">.
 * [[image:larval development.png width="734" height="214" align="center"]] ||
 * Figure 12: Different stages of development of button snail. Illustration by Jenny, with reference to 18] ||

=<span style="color: #0157fc; font-family: Arial,Helvetica,sans-serif; font-size: 15pt;">4. Anthropogenic threats = <span style="font-family: Arial,Helvetica,sans-serif; font-size: 10pt;">**<span style="font-family: Arial,Helvetica,sans-serif; font-size: 13pt; font-variant: small-caps;">Global threats ** <span style="font-family: Arial,Helvetica,sans-serif; font-size: 10pt;"> <span style="font-family: Arial,Helvetica,sans-serif; font-size: 11pt;">In the early 20th century, it was said that millions of button snails were exported from India to Europe for shell craft industry: their <span style="font-family: Arial,Helvetica,sans-serif; font-size: 15px;"> button-like shape and wide variety of colour patterns make them very attractive <span style="font-family: Arial,Helvetica,sans-serif; font-size: 10pt; vertical-align: super;">19] <span style="font-family: Arial,Helvetica,sans-serif; font-size: 11pt;">.Therefore, over-collection may be a possible threat to button snails. They are often used as accessories in aquarium and home decorations (Figure 13). Human consumption is another threat: vendors may use aromatic thorns (//Acacia pennata//) to pry the meat out from the shell <span style="font-family: Arial,Helvetica,sans-serif; font-size: 10pt; vertical-align: super;">1] <span style="font-family: Arial,Helvetica,sans-serif; font-size: 10pt;">. In addition, increased turbidity from beach sand mining may interfere with the suspension feeding of the snail and the settlement of its juvenile 3]. Marine pollution may also render sand to be non-habitable by button snails as they avoid acid-treated sand 20] <span style="font-family: Arial,Helvetica,sans-serif; font-size: 11pt;">.
 * [[image:screen shot shell for sale.png link="http://www.americanaquariumproducts.com/UmboniumShells.html"]] ||
 * <span style="font-family: Arial,Helvetica,sans-serif; font-size: 10pt;">Figure 13: Screenshot of button snail for sale on @http://www.americanaquariumproducts.com/UmboniumShells.html ||

<span style="font-family: Arial,Helvetica,sans-serif; font-size: 10pt;"> **<span style="font-family: Arial,Helvetica,sans-serif; font-size: 13pt; font-variant: small-caps;">Local threats in Singapore ** <span style="font-family: Arial,Helvetica,sans-serif; font-size: 11pt;">Button snail used to be highly abundant in the 1960s, but due to habitat loss and degradation, its populations have declined drastically <span style="font-family: Arial,Helvetica,sans-serif; font-size: 10pt; vertical-align: super;">21] <span style="font-family: Arial,Helvetica,sans-serif; font-size: 11pt;">. It is now listed as ‘vulnerable’ on Singapore Red Data Book 2008 <span style="font-family: Arial,Helvetica,sans-serif; font-size: 10pt; vertical-align: super;">22] <span style="font-family: Arial,Helvetica,sans-serif; font-size: 11pt;">.

=<span style="color: #0157fc; font-family: Arial,Helvetica,sans-serif; font-size: 15pt;">5. Taxonomy and systematics =

**<span style="font-family: Arial,Helvetica,sans-serif; font-size: 13pt;">(i) **<span style="font-family: Arial,Helvetica,sans-serif; font-size: 13pt; font-variant: small-caps;">Nomenclature
<span style="font-family: Arial,Helvetica,sans-serif; font-size: 11pt;">**Scientific name**: //Umbonium vestiarium// (Linnaeus, 1758) <span style="font-family: Arial,Helvetica,sans-serif; font-size: 11pt;">**Common names**: Button snail, Button top ==**<span style="font-family: Arial,Helvetica,sans-serif; font-size: 13pt;">(ii) **<span style="font-family: Arial,Helvetica,sans-serif; font-size: 13pt; font-variant: small-caps;">Diagnostic features == <span style="font-family: Arial,Helvetica,sans-serif; font-size: 11pt;">Shell round, flat, lenticular, much wider the long <span style="font-family: Arial,Helvetica,sans-serif; font-size: 10pt; vertical-align: super;">1] <span style="font-family: Arial,Helvetica,sans-serif; font-size: 11pt;">. Spire low and spire whorls without concentric grooves; periphery of whorls uniformly rounded <span style="font-family: Arial,Helvetica,sans-serif; font-size: 10pt; vertical-align: super;">1] <span style="font-family: Arial,Helvetica,sans-serif; font-size: 11pt;">. Umbilical surface flattened and thickened by calcareous deposits that fill the umbilicus <span style="font-family: Arial,Helvetica,sans-serif; font-size: 10pt; vertical-align: super;">1] <span style="font-family: Arial,Helvetica,sans-serif; font-size: 11pt;">. Shell glossy with various patterns and colours; umbilical callus generally of different colour from the shell <span style="font-family: Arial,Helvetica,sans-serif; font-size: 10pt; vertical-align: super;">1] <span style="font-family: Arial,Helvetica,sans-serif; font-size: 11pt;">. Operculum circular, relatively thick, and completely close the aperture <span style="font-family: Arial,Helvetica,sans-serif; font-size: 10pt; vertical-align: super;">31] <span style="font-family: Arial,Helvetica,sans-serif; font-size: 11pt;">. Radula rhipidoglossan, not so developed, reduced in tooth cusps as it is a filter-feeder <span style="font-family: Arial,Helvetica,sans-serif; font-size: 10pt; vertical-align: super;">10,31] <span style="font-family: Arial,Helvetica,sans-serif; font-size: 11pt;">. Ctenidium monopectinate, and attached to mantle throughout its length <span style="font-family: Arial,Helvetica,sans-serif; font-size: 10pt; vertical-align: super;">10,31] <span style="font-family: Arial,Helvetica,sans-serif; font-size: 11pt;">.
 * <span style="font-family: Arial,Helvetica,sans-serif; font-size: 11pt;">Taxonavigation: **
 * <span style="font-family: Arial,Helvetica,sans-serif; font-size: 10pt;">Kingdom || <span style="font-family: Arial,Helvetica,sans-serif; font-size: 10pt;">Animalia ||
 * <span style="font-family: Arial,Helvetica,sans-serif; font-size: 10pt;">Phylum || <span style="font-family: Arial,Helvetica,sans-serif; font-size: 10pt;">Mollusca ||
 * <span style="font-family: Arial,Helvetica,sans-serif; font-size: 10pt;">Class || <span style="font-family: Arial,Helvetica,sans-serif; font-size: 10pt;">Gastropoda ||
 * <span style="font-family: Arial,Helvetica,sans-serif; font-size: 10pt;">Subclass || <span style="font-family: Arial,Helvetica,sans-serif; font-size: 10pt;">Vetigastropoda ||
 * <span style="font-family: Arial,Helvetica,sans-serif; font-size: 10pt;">Order || <span style="font-family: Arial,Helvetica,sans-serif; font-size: 10pt;">Archaeogastropoda ||
 * <span style="font-family: Arial,Helvetica,sans-serif; font-size: 10pt;">Family || <span style="font-family: Arial,Helvetica,sans-serif; font-size: 10pt;">Trochidae ||
 * <span style="font-family: Arial,Helvetica,sans-serif; font-size: 10pt;">Genus || //<span style="font-family: Arial,Helvetica,sans-serif; font-size: 10pt;">Umbonium // ||
 * <span style="font-family: Arial,Helvetica,sans-serif; font-size: 10pt;">Species || //<span style="font-family: Arial,Helvetica,sans-serif; font-size: 10pt;">U. vestiarium // ||
 * <span style="font-family: Arial,Helvetica,sans-serif; font-size: 11pt;">Synonyms: **
 * <span style="font-family: Arial,Helvetica,sans-serif; font-size: 10pt;">//Trochus vestiarius// Linnaeus, 1758 ||
 * <span style="font-family: Arial,Helvetica,sans-serif; font-size: 10pt;">//Globulus vestiarius// Schumacher, 1817 ||
 * <span style="font-family: Arial,Helvetica,sans-serif; font-size: 10pt;">//Rotella lineolata// Lamarck, 1822 ||
 * [[image:button snail diagnostic features.png]] ||
 * Figure 14: Selected identifying features of //Umbonium vestiarium//. Photo: © 2015 Jenny, with reference to <span style="font-family: Arial,Helvetica,sans-serif;">1] ||

**<span style="font-family: Arial,Helvetica,sans-serif; font-size: 13pt;">(iii) **<span style="font-family: Arial,Helvetica,sans-serif; font-size: 13pt; font-variant: small-caps;">Taxonomic history
<span style="font-family: Arial,Helvetica,sans-serif; font-size: 11pt;">//Umbonium vestiarium// was originally described by Linnaeus in 1758 using the name //Trochus vestiarius// and he noted that the umbilicus was filled with callus (Figure 15) <span style="font-family: Arial,Helvetica,sans-serif; font-size: 10pt; vertical-align: super;">23] <span style="font-family: Arial,Helvetica,sans-serif; font-size: 11pt;">. The genus //Globulus//, assigned by Schumacher in 1817, is an objective synonym of genus //Umbonium//, meaning that both //Globulus// and //Umbonium// contain the same species (i.e. //U. vestiarium//), but //Umbonium// <span style="font-family: Arial,Helvetica,sans-serif; font-size: 15px;">(Link, 1807) <span style="font-family: Arial,Helvetica,sans-serif; font-size: 11pt;">has precedence because it is older. Later on, Lamarck thought that the snail had "remarkably callous" lower surface compared to other Trochus, so he gave a new name, //<span style="font-family: Arial,Helvetica,sans-serif;"> Rotella lineolata //<span style="font-family: Arial,Helvetica,sans-serif; font-size: 11pt;">, in 1822 (Figure 16) <span style="font-family: Arial,Helvetica,sans-serif; font-size: 10pt; vertical-align: super;">24] <span style="font-family: Arial,Helvetica,sans-serif; font-size: 11pt;">. He also took the liberty to change the species name from vestiarius to lineolata, something that he has often done for other genera as well, creating confusion <span style="font-family: Arial,Helvetica,sans-serif; font-size: 10pt; vertical-align: super;">25] <span style="font-family: Arial,Helvetica,sans-serif; font-size: 11pt;">. Subsequently, Dr Arthur Adams placed the snail under genus //Umbonium// in 1851 (Figure 17) <span style="font-family: Arial,Helvetica,sans-serif; font-size: 10pt; vertical-align: super;">26] <span style="font-family: Arial,Helvetica,sans-serif; font-size: 11pt;">. ||
 * [[image:original description Linnaeus.png width="474" height="373" link="http://gdz.sub.uni-goettingen.de/en/dms/loader/img/?PPN=PPN362053006&DMDID=DMDLOG_0047&LOGID=LOG_0047&PHYSID=PHYS_0762"]] ||
 * Figure 15: Description by Linnaeus in 1758. Extract from Göttinger Digitalisierungszentrum (pending approval). Translation by Jenny. |||| Figure 16: Description on //Rotella lineolata//. Image from the Biodiversity Heritage Library. Digitized by Natural History Museum Library, London ||
 * [[image:description 1851.png width="615" height="181" align="center" link="http://www.biodiversitylibrary.org/page/12859338#page/690/mode/1up"]] ||
 * Figure 17: Description on //Umbonium vestiarium//. Image from the Biodiversity Heritage Library. Digitized by Natural History Museum Library, London ||

<span style="font-family: Arial,Helvetica,sans-serif; font-size: 13pt;">(iv) **<span style="font-family: Arial,Helvetica,sans-serif; font-size: 13pt; font-variant: small-caps;">Type information **
<span style="font-family: Arial,Helvetica,sans-serif; font-size: 11pt;">No valid holotype was found for //Umbonium vestiarium//. This is because the specimen (//Trochus vestiarius//) that was assigned as the type actually referred to //<span style="font-family: Arial,Helvetica,sans-serif;"> Umbonium callous //<span style="font-family: Arial,Helvetica,sans-serif; font-size: 11pt;">; nevertheless, that specimen is a valid holotype for genus //<span style="font-family: Arial,Helvetica,sans-serif; font-size: 11pt;">Umbonium //<span style="font-family: Arial,Helvetica,sans-serif; font-size: 11pt;"> as it was the first species described for the genus <span style="font-family: Arial,Helvetica,sans-serif; font-size: 10pt; vertical-align: super;">27,28] <span style="font-family: Arial,Helvetica,sans-serif; font-size: 11pt;">. This specimen is kept in Uppsala University Zoological Museum <span style="font-family: Arial,Helvetica,sans-serif; font-size: 10pt; vertical-align: super;">28] <span style="font-family: Arial,Helvetica,sans-serif; font-size: 11pt;">. No record of syntypes and lectotypes of //U. vestiarium// could be found. Its type locality, as appointed by Linnaeus in his original description, is Mediterrranean, Asia, and China <span style="font-family: Arial,Helvetica,sans-serif; font-size: 10pt; vertical-align: super;">23] <span style="font-family: Arial,Helvetica,sans-serif; font-size: 11pt;">.

<span style="font-family: Arial,Helvetica,sans-serif; font-size: 13pt;">(v) <span style="font-family: Arial,Helvetica,sans-serif; font-size: 13pt; font-variant: small-caps;"> Phylogeny
<span style="font-family: Arial,Helvetica,sans-serif; font-size: 11pt;">Traditionally, phylogeny of family Trochidae was constructed based on morphology such as radula and ctenidium. For instance, subfamily Umboniinae, Lirulariinae, and Halistylinae were grouped together owing to them having monopectinate ctenidium and reduced radula <span style="font-family: Arial,Helvetica,sans-serif; font-size: 10pt; vertical-align: super;">32] <span style="font-family: Arial,Helvetica,sans-serif; font-size: 11pt;">. However, recent molecular study has revealed that Lirularia is nested within Umboniinae <span style="font-family: Arial,Helvetica,sans-serif; font-size: 10pt; vertical-align: super;">29] <span style="font-family: Arial,Helvetica,sans-serif; font-size: 11pt;">. Using <span style="font-family: Arial,Helvetica,sans-serif; font-size: 15px;">concatenated sequences from 28S rRNA, 12S rRNA, 16S rRNA, and CO1, this study <span style="font-family: Arial,Helvetica,sans-serif; font-size: 11pt;"> also shows that <span style="font-family: Arial,Helvetica,sans-serif; font-size: 15px;">subfamily Umboniinae —<span style="font-family: Arial,Helvetica,sans-serif; font-size: 15px;">represented by closely related species of //Umbonium vestiarium//, namely //<span style="font-family: Arial,Helvetica,sans-serif; font-size: 15px;">Umbonium giganteum //<span style="font-family: Arial,Helvetica,sans-serif; font-size: 15px;">, //<span style="font-family: Arial,Helvetica,sans-serif; font-size: 15px;">Umbonium costatum //<span style="font-family: Arial,Helvetica,sans-serif; font-size: 15px;">, and //<span style="font-family: Arial,Helvetica,sans-serif; font-size: 15px;">Umbonium monileferum //—<span style="font-family: Arial,Helvetica,sans-serif; font-size: 15px;">is <span style="font-family: Arial,Helvetica,sans-serif; font-size: 11pt;"> a monophyletic group <span style="font-family: Arial,Helvetica,sans-serif; font-size: 10pt; vertical-align: super;">29] <span style="font-family: Arial,Helvetica,sans-serif; font-size: 11pt;">. <span style="font-family: Arial,Helvetica,sans-serif; font-size: 15px;">No phylogenetic record of //<span style="font-family: Arial,Helvetica,sans-serif; font-size: 15px;">U. vestiarium //<span style="font-family: Arial,Helvetica,sans-serif; font-size: 15px;">, allowing it to be placed on phylogenetic trees, could be found; more research is needed to shed light on the phylogeny of //<span style="font-family: Arial,Helvetica,sans-serif; font-size: 15px;">U. vestiarium //<span style="font-family: Arial,Helvetica,sans-serif; font-size: 11pt;">.
 * [[image:phylogeny copy.png width="800" height="1018"]] ||
 * Figure 18: Molecular phylogeny of Trochidae and Calliostomatidae, with subfamily Umboniinae highlighted in blue, based on concatenated sequences from four genes using Bayesian analysis with uncorrelated relaxed, lognormal clock using BEAST. Source: Williams //et al//., 2010<span style="font-family: Arial,Helvetica,sans-serif;">29] (Permission granted) ||

=<span style="color: #0157fc; font-family: Arial,Helvetica,sans-serif; font-size: 15pt;">6. External resources =
 * [|WoRMS (World Register of Marine Species)]
 * WildSingapore
 * [|EOL (Encyclopedia of Life)]
 * SeaLife
 * GenBank records

=<span style="color: #0157fc; font-family: Arial,Helvetica,sans-serif; font-size: 15pt;">7. References = <span style="font-family: Arial,Helvetica,sans-serif; font-size: 10pt;">[1] Carpenter, K. E., & V. H. Niem, 1998. //FAO species identification guide for fishery purposes. The living marine resources of the Western Central Pacific. Volume 1. Seaweeds, corals, bivalves and gastropods//. Food and Agriculture Organization of The United Nations, Rome. 686 pp. <span style="font-family: Arial,Helvetica,sans-serif;">[2] <span style="font-family: Arial,Helvetica,sans-serif;">Leimar, O., 2005. The evolution of phenotypic polymorphism: randomized strategies versus evolutionary branching. //The American Naturalist//, 165(6): 669-681. <span style="font-family: Arial,Helvetica,sans-serif;">[3] <span style="font-family: Arial,Helvetica,sans-serif; font-size: 10pt;">Sivadas, S., B. Ingole, & A. Sen, 2012. Some ecological aspects and potential threats to an intertidal gastropod, //Umbonium vestiarium//. //Journal of Environmental Biology//, 33: 1039-1044. <span style="font-family: Arial,Helvetica,sans-serif;">[4] <span style="font-family: Arial,Helvetica,sans-serif; font-size: 10pt;">Allen, J.A. & B. C. Clarke, 1984. Frequency-dependent selection – Homage to Poulton, E.B”. //Biological Journal of the Linnean Society//, 23:15-18. <span style="font-family: Arial,Helvetica,sans-serif;">[5] <span style="font-family: Arial,Helvetica,sans-serif; font-size: 10pt;">Miura, O., S. Nishi, & S. Chiba, 2007. Temperature-related diversity of shell colour in the intertidal gastropod Batillaria. //Journal of Molluscan Studies//, 73(3): 235-240. <span style="font-family: Arial,Helvetica,sans-serif;">[6] <span style="font-family: Arial,Helvetica,sans-serif;">Tamaki, A., & T. Kikuchi, 1983. Spatial arrangement of macrobenthic assemblages on an intertidal sand flat, Tomioka Bay, west Kyushu. //<span style="font-family: Arial,Helvetica,sans-serif;">Publications from Amakusa Marine Biology Laboratory, Kyushu University, //<span style="font-family: Arial,Helvetica,sans-serif;"> 7: 41-60. <span style="font-family: Arial,Helvetica,sans-serif;">[7] <span style="background-color: #ffffff; color: #222222; font-family: Arial,sans-serif;">Kalyanasundaram, N., S. S. Ganti, & A. A. Karande, 1972. The habitat and the habitat-selection by //Umbonium vestiarium// L. //<span style="color: #222222; font-family: Arial,sans-serif;">Proceedings of Indian National Science Academy, //<span style="background-color: #ffffff; color: #222222; font-family: Arial,sans-serif;">38: 275-287. <span style="font-family: Arial,Helvetica,sans-serif;">[8] <span style="font-family: Arial,Helvetica,sans-serif;">" //<span style="font-family: Arial,Helvetica,sans-serif;">Umbonium vestiarium //<span style="font-family: Arial,Helvetica,sans-serif;"> (Linnaeus, 1758)". Lee Kong Chian Natural History Museum, n.d. URL: @http://lkcnhm.nus.edu.sg/dna/organisms/details/847 (accessed on 7 November 2015) <span style="font-family: Arial,Helvetica,sans-serif;">[9] <span style="font-family: Arial,Helvetica,sans-serif;"> "Umbonium vestiarium Linnaeus 1758". GBIF Secretariat: GBIF Backbone Taxonomy, 2013. URL: @http://www.gbif.org/species/4358247 (accessed on 11 November 2015) <span style="background-color: #ffffff; color: #222222; font-family: Arial,sans-serif;">[10] <span style="font-family: Arial,Helvetica,sans-serif;">Fretter, V., 1975. //<span style="font-family: Arial,Helvetica,sans-serif;">Umbonium vestiarium //<span style="font-family: Arial,Helvetica,sans-serif;">, a filter‐feeding trochid. //<span style="font-family: Arial,Helvetica,sans-serif;">Journal of Zoology //<span style="font-family: Arial,Helvetica,sans-serif;">, 177(4): 541-552. <span style="font-family: Arial,Helvetica,sans-serif;">[11] Adams, A., 1860. On the animal of //Umbonium vestiarium//. //Annals and Magazine of Natural History//, 6(3): 288-289 <span style="font-family: Arial,Helvetica,sans-serif;">[12] <span style="background-color: #ffffff; color: #222222; font-family: Arial,sans-serif;">Ansell, A. D., 1969. Escape responses of 3 Indian mollusks. //<span style="color: #222222; font-family: Arial,sans-serif;">Veliger //<span style="background-color: #ffffff; color: #222222; font-family: Arial,sans-serif;">, 12(2): 157-159. <span style="font-family: Arial,Helvetica,sans-serif;">[13] <span style="font-family: Arial,Helvetica,sans-serif; font-size: 10pt;">Heller, J., 2015. //Sea Snails: A natural history//. Springer, Switzerland. 354 pp. <span style="font-family: Arial,Helvetica,sans-serif;">[14] <span style="background-color: #ffffff; color: #222222; font-family: Arial,sans-serif;">Berry, A. J., 1984. //Umbonium vestiarium// (L.)(Gastropoda, Trochacea) as the food source for naticid gastropods and a starfish on a Malaysian sandy shore. //<span style="color: #222222; font-family: Arial,sans-serif;">Journal of Molluscan Studies //<span style="background-color: #ffffff; color: #222222; font-family: Arial,sans-serif;">, <span style="color: #222222; font-family: Arial,sans-serif;">50 <span style="background-color: #ffffff; color: #222222; font-family: Arial,sans-serif;">(1): 1-7. <span style="font-family: Arial,Helvetica,sans-serif;">[15] <span style="font-family: Arial,Helvetica,sans-serif;">Berry, A. J., 1986. Daily, tidal, and two-weekly spawning periodicity and brief pelagic dispersal in the tropical intertidal gastropod //<span style="font-family: Arial,Helvetica,sans-serif;">Umbonium vestiarium //<span style="font-family: Arial,Helvetica,sans-serif;"> (L.). //<span style="font-family: Arial,Helvetica,sans-serif;">Journal of experimental marine biology and ecology //<span style="font-family: Arial,Helvetica,sans-serif;">, 95(3): 211-223. <span style="background-color: #ffffff; color: #222222; font-family: Arial,sans-serif;">[16] <span style="font-family: Arial,Helvetica,sans-serif;">Ryland, J. S., & P. A. Tyler (eds.), 1989. //<span style="font-family: Arial,Helvetica,sans-serif;">Reproduction, Genetics and Distributions of Marine Organisms: 23rd European Marine Biology Symposium, School of Biological Sciences, University of Wales, Swansea //<span style="font-family: Arial,Helvetica,sans-serif;">. Olsen & Olsen, Denmark. 469 pp. <span style="background-color: #ffffff; color: #222222; font-family: Arial,sans-serif;">[17] <span style="background-color: #ffffff; color: #222222; font-family: Arial,sans-serif;">Berry, A. J., 1987. Reproductive cycles, egg production and recruitment in the Indo-Pacific intertidal gastropod //Umbonium vestiarium// (L.). //<span style="color: #222222; font-family: Arial,sans-serif;">Estuarine, Coastal and Shelf Science //<span style="background-color: #ffffff; color: #222222; font-family: Arial,sans-serif;">, <span style="color: #222222; font-family: Arial,sans-serif;">24 <span style="background-color: #ffffff; color: #222222; font-family: Arial,sans-serif;">(5): 711-723. <span style="background-color: #ffffff; color: #222222; font-family: Arial,sans-serif;">[18] Hickman, C. S., 1992. Reproduction and development of trochacean gastropods. //Veliger,// 35(4): 245-272. <span style="background-color: #ffffff; color: #222222; font-family: Arial,sans-serif;">[19] <span style="background-color: #ffffff; color: #222222; font-family: Arial,sans-serif;"> Hornell, J., 1951. //<span style="background-color: #ffffff; color: #222222; font-family: Arial,sans-serif;">Indian molluscs //<span style="background-color: #ffffff; color: #222222; font-family: Arial,sans-serif;">. Bombay Natural History Society, India. 96 pp <span style="background-color: #ffffff; color: #222222; font-family: Arial,sans-serif;">[20] <span style="background-color: #ffffff; color: #222222; font-family: Arial,sans-serif;">Kalyanasundaram, N., S. S. Ganti, & A. A. Karande, 1972. The habitat and the habitat-selection by //Umbonium vestiarium// L. //<span style="color: #222222; font-family: Arial,sans-serif;">Proceedings of Indian National Science Academy, //<span style="background-color: #ffffff; color: #222222; font-family: Arial,sans-serif;">38: 275-287. <span style="background-color: #ffffff; color: #222222; font-family: Arial,sans-serif;">[21] <span style="background-color: #ffffff; color: #222222; font-family: Arial,sans-serif; font-size: 10pt;">" //<span style="color: #222222; font-family: Arial,Helvetica,sans-serif;">Umbonium vestiarium //<span style="background-color: #ffffff; color: #222222; font-family: Arial,Helvetica,sans-serif;"> (Linnaeus, 1758)". Flora & Fauna Web, n.d. 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