''Anentome helena'', common name assassin snail or bumblebee snail, is a

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

freshwater snail Freshwater snails are gastropod mollusks that live in fresh water. There are many different families. They are found throughout the world in various habitats, ranging from ephemeral pools to the largest lakes, and from small seeps and springs t ...

with an operculum, an

aquatic Aquatic means relating to water; living in or near water or taking place in water; does not include groundwater, as "aquatic" implies an environment where plants and animals live. Aquatic(s) may also refer to: * Aquatic animal, either vertebrate ...

gastropod Gastropods (), commonly known as slugs and snails, belong to a large Taxonomy (biology), taxonomic class of invertebrates within the phylum Mollusca called Gastropoda (). This class comprises snails and slugs from saltwater, freshwater, and fro ...

in the family

Nassariidae The Nassariidae, Nassa mud snails (US), or dog whelks (UK) are a taxonomic family of small to medium-sized snails, mostly marine gastropod mollusks in the clade Neogastropoda. These snails have rounded shells with a high spire, an oval ap ...

, most of which are marine.

Distribution

The assassin snail is found throughout

southeast Asia Southeast Asia is the geographical United Nations geoscheme for Asia#South-eastern Asia, southeastern region of Asia, consisting of the regions that are situated south of China, east of the Indian subcontinent, and northwest of the Mainland Au ...

, especially in

Malaysia Malaysia is a country in Southeast Asia. Featuring the Tanjung Piai, southernmost point of continental Eurasia, it is a federation, federal constitutional monarchy consisting of States and federal territories of Malaysia, 13 states and thre ...

Thailand Thailand, officially the Kingdom of Thailand and historically known as Siam (the official name until 1939), is a country in Southeast Asia on the Mainland Southeast Asia, Indochinese Peninsula. With a population of almost 66 million, it spa ...

, and in

Lake Toba Lake Toba (, Toba Batak: ᯖᯀᯬ ᯖᯬᯅ; romanized: ''Tao Toba'') is a large natural lake in North Sumatra, Indonesia, occupying the caldera of the Toba supervolcano. The lake is located in the middle of the northern part of the island of ...

on the

Indonesia Indonesia, officially the Republic of Indonesia, is a country in Southeast Asia and Oceania, between the Indian Ocean, Indian and Pacific Ocean, Pacific oceans. Comprising over List of islands of Indonesia, 17,000 islands, including Sumatra, ...

n island

Sumatra Sumatra () is one of the Sunda Islands of western Indonesia. It is the largest island that is fully within Indonesian territory, as well as the list of islands by area, sixth-largest island in the world at 482,286.55 km2 (182,812 mi. ...

. Boon-ngam P., Sriyarun J., Tanamai S. & Dumrongrojwattana P. (PDF file created 12 January 2010). "การศึกษาเบืองต้ นความหลากชนิดของหอยทากบก และหอยนําจืดในจังหวัดสระแก้ ว Preliminary taxonomic study of land snail and freshwater mollusk species in Sakaeo Province, Eastern Thailand". 10 pp., pages unnumbered
PDF

Description

The assassin snail typically grows to in size, though this is dependent on food sources; they are usually smaller when kept in an aquarium. The shell, which is conical in shape, often consists of dark brown and yellowish tan bands, leading to some people to refer to it as the bumble bee snail, a name also applied to the marine snail '' Engina mendicaria''. Some specimens have been identified with completely brown shells, lacking banding.

Ecology

Habitat

The assassin snail spends much of its time buried in substrate. They are least active during mid-day; however, they can sense food and will become active if fed.

Feeding habits

Like all snails in the clade Neogastropoda, the assassin snail is carnivorous. It feeds on worms and gastropods, garnering it the common moniker of "assassin snail" for its habit of eating other snails. The snail will often feed on larger snails, often burying itself in order to ambush prey. ''Anentome helena'' may be a serious threat to native freshwater gastropods in countries when introduced.

Life cycle

In ''A. helena'' the sexes are separated, meaning there are male and female individuals which are not

hermaphroditic A hermaphrodite () is a sexually reproducing organism that produces both male and female gametes. Animal species in which individuals are either male or female are gonochoric, which is the opposite of hermaphroditic. The individuals of many ...

. Currently it is not known how to identify which is male and which is female. Both males and females seem to be the same size and shape. When a male and female mate, they lock together for many hours. The female lays several clear egg capsules which are square in shape and approximately in width and height. Each egg capsule contains a single small yellow egg. The egg capsules are generally laid on solid surfaces such as plastic and often on the base of plants. Fertile eggs usually hatch within a few weeks.

Parasites

Like many snail species, ''Anentome helena'' can serve as an

intermediate host In biology and medicine, a host is a larger organism that harbours a smaller organism; whether a parasitic, a mutualistic, or a commensalist ''guest'' (symbiont). The guest is typically provided with nourishment and shelter. Examples include ...

to trematode parasites. It has been confirmed as an intermediate host to ''

Echinostoma revolutum ''Echinostoma revolutum'' is a trematode parasite of which the adults can infect birds and mammals, including humans. In humans, it causes echinostomiasis.. Distribution ''Echinostoma revolutum'' is the most widely distributed species of the kn ...

'' in the

Chiang Mai Chiang Mai, sometimes written as Chiengmai or Chiangmai, is the largest city in northern Thailand, the capital of Chiang Mai province and the List of municipalities in Thailand#Largest cities by urban population, second largest city in Thailan ...

province in Thailand.

Human use

''A. helena'' is a part of ornamental

pet trade Wildlife trade refers to the exchange of products derived from non-domesticated animals or plants usually extracted from their natural environment or raised under controlled conditions. It can involve the trade of living or dead individuals, tis ...

for freshwater aquaria, where they are used to control populations of unwanted small snail species such as the

Malaysian trumpet snail The red-rimmed melania (''Melanoides tuberculata''), also known as the Malayan livebearing snail or Malayan/Malaysian trumpet snail (often abbreviated to MTS by aquarists), is a species of freshwater snail with an Operculum (gastropod), operculu ...

References

{{Taxonbar, from1=Q106170753, from2=Q1372423 Nassariidae Gastropods described in 1847