Anaspidea

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Anaspidea
Aplysia californica.jpg
Aplysia californica , a typical sea hare displaying inking behavior
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Mollusca
Class: Gastropoda
Subclass: Heterobranchia
Clade: Euopisthobranchia
Clade: Anaspidea
P. Fischer, 1883
Families
Synonyms

Aplysiomorpha

The clade Anaspidea, commonly known as sea hares ( Aplysia species and related genera), are medium-sized to very large opisthobranch gastropod molluscs with a soft internal shell made of protein. These are marine gastropod molluscs in the superfamilies Aplysioidea and Akeroidea.

Contents

The common name "sea hare" is a direct translation from Latin : lepus marinus, as the animal's existence was known in Roman times. The name derives from their rounded shape and from the two long rhinophores that project upward from their heads and that somewhat resemble the ears of a hare.

Taxonomy

Many older textbooks and websites refer to this suborder as "Anaspidea". The original author Paul Henri Fischer described the taxon Anaspidea at unspecified rank above family. [1] In 1925 Johannes Thiele established the taxon Anaspidea as a suborder.

2005 taxonomy

Since the taxon Anaspidea was not based on an existing genus, this name is no longer available according to the rules of the ICZN.[ citation needed ] Anaspidea has been replaced in the new Taxonomy of the Gastropoda (Bouchet & Rocroi, 2005) by the clade Aplysiomorpha.

The scientific name for the order in which they used to be classified, the Anaspidea, is derived from the Greek for "without a shield" and refers to the lack of the characteristic head shield found in the cephalaspidean opisthobranchs. Many anaspideans have only a thin, internal and much-reduced shell with a small mantle cavity; some have no shell at all. All species have a radula and gizzard plates.

2010 taxonomy

Jörger et al. (2010) [2] have moved this taxon (named as Anaspidea) to Euopisthobranchia.

2017 taxonomy

The name "Aplysiomorpha" was preferred by Bouchet and Rocroi (2005) over "Anaspidea Fischer", 1883, but the authors now agree that there is a consistent usage for Anaspidea in the recent literature and that the older name must be preferred. [3]

Description

Sea hares are mostly rather large, bulky creatures when adults. Juveniles are mainly unobserved on the shoreline. The biggest species, Aplysia vaccaria , can reach a length of 75 centimetres (30 in) and a weight of 14 kilograms (31 lb) and is arguably the largest gastropod species. [4]

Sea hares have soft bodies with an internal shell, and like all opisthobranch molluscs, they are hermaphroditic. Unlike many other gastropods, they are more or less bilaterally symmetrical in their external appearance. The foot has lateral projections, or "parapodia". [5]

Life habits

Sea Hare Dolabella auricularia at Big Island of Hawaii Sea hare DSC01663.jpg
Sea Hare Dolabella auricularia at Big Island of Hawaii

Sea hares are herbivorous, and are typically found on seaweed in shallow water. Some young sea hares seemingly are capable of burrowing in soft sediment, leaving only their rhinophores and mantle opening showing. Sea hares have an extremely good sense of smell. They can follow even the faintest scent using their rhinophores, which are extremely sensitive chemoreceptors.

Their color corresponds with the color of the seaweed they eat: red sea hares have been feeding on red seaweed. This camouflages them from predators. When disturbed, a sea hare can release ink from its ink glands, providing a fluid, smoke-like toxic screen, adversely affecting its predators' olfactory senses while acting as a powerful deterrent. The toxic ink may be white, purple, or red, depending on the pigments in their seaweed food source and lightens in color as it spreads, diluted by seawater. Their skin contains a similar toxin that renders sea hares largely inedible to many predators.[ citation needed ] In addition to the colored ink, sea hares can secrete a clear slime akin to that released defensively by hagfish which physically plugs the olfactory receptors of predators like lobsters. [6] [7]

Some sea hares can employ jet propulsion as a locomotion and others move like stingrays but with greater fluttering fluidity in their jelly-like "wings". In the moving marine environment and without the sophisticated cognitive machinery of the cephalopods, their motion appears to be somewhat erratic, but they do reach their goals, such as the seabed, according to the wave-action, currents, or calmness of their area. [8] [9]

Human use

Sea hares are consumed in several parts of the world. An example may be "酱爆海兔" [10] ( jiàng bào hǎi tù ), lit. "sauce-fried sea hare", a Chinese dish featuring sea hare and occasionally squid quickly fried in a sauce. In Hawaii, sea hares, or kualakai, are typically cooked in an imu wrapped in ti leaves.[ citation needed ]

Aplysia californica is a species of sea hare noteworthy for its use in studies of the neurobiology of learning and memory, due to its unusually large axons. It is especially associated with the work of Nobel Laureate Eric Kandel. [11] Research surrounding the aplysia gill and siphon withdrawal reflex may be of particular interest with respect to this. [12]

Reef aquaria

Sea hares are often used as a method of eradicating nuisance algae and cyanobacteria ("red slime algae") in reef aquaria. The hares usually do an excellent job, but when they have eaten all of the algae and cyanobacteria, they often shrink from starvation and eventually starve to death. Many reef-keeping clubs have started programs where groups of hobbyists "share" a single sea hare among a large group.

Related Research Articles

<span class="mw-page-title-main">Nudibranch</span> Order of gastropods

Nudibranchs are a group of soft-bodied marine gastropod molluscs that shed their shells after their larval stage. They are noted for their often extraordinary colours and striking forms, and they have been given colourful nicknames to match, such as "clown", "marigold", "splendid", "dancer", "dragon", and "sea rabbit". Currently, about 3,000 valid species of nudibranchs are known.

<span class="mw-page-title-main">California sea hare</span> Species of gastropod

The California sea hare is a species of sea slug in the sea hare family, Aplysiidae. It is found in the Pacific Ocean, off the coast of California in the United States and northwestern Mexico.

<span class="mw-page-title-main">Sea slug</span> Group of marine gastropods

Sea slug is a common name for some marine invertebrates with varying levels of resemblance to terrestrial slugs. Most creatures known as sea slugs are gastropods, i.e. they are sea snails that over evolutionary time have either completely lost their shells, or have seemingly lost their shells due to having a greatly reduced or internal shell. The name "sea slug" is most often applied to nudibranchs, as well as to a paraphyletic set of other marine gastropods without obvious shells.

<span class="mw-page-title-main">Opisthobranchia</span> Informal group of gastropods

Opisthobranchs is a now informal name for a large and diverse group of specialized complex gastropods which used to be united in the subclass Opisthobranchia. That taxon is no longer considered to represent a monophyletic grouping.

<span class="mw-page-title-main">Aplysiidae</span> Family of gastropods

Aplysiidae is the only family in the superfamily Aplysioidea, within the clade Anaspidea. These animals are commonly called sea hares because, unlike most sea slugs, they are often quite large, and when they are underwater, their rounded body shape and the long rhinophores on their heads mean that their overall shape resembles that of a sitting rabbit or hare. Sea hares are however sea snails with shells reduced to a small plate hidden between the parapodia, and some species are extremely large. The Californian black sea hare, Aplysia vaccaria is arguably the largest living gastropod species, and is certainly the largest living heterobranch gastropod.

<span class="mw-page-title-main">Heterobranchia</span> Clade of gastropods

Heterobranchia, the heterobranchs, is a taxonomic clade of snails and slugs, which includes marine, aquatic and terrestrial gastropod mollusks.

<span class="mw-page-title-main">Cephalaspidea</span> Order of gastropods

The order Cephalaspidea, also known as the headshield slugs and bubble snails, is a major taxon of sea slugs and bubble snails, marine gastropod mollusks within the larger clade Euopisthobranchia. Bubble shells is another common name for these families of marine gastropods, some of which have thin bubble-like shells. This clade contains more than 600 species.

<span class="mw-page-title-main">Rhinophore</span> Anatomy of groups of marine gastropods

A rhinophore is one of a pair of chemosensory club-shaped, rod-shaped or ear-like structures which are the most prominent part of the external head anatomy in sea slugs, marine gastropod opisthobranch mollusks such as the nudibranchs, sea hares (Aplysiomorpha), and sap-sucking sea slugs (Sacoglossa).

<i>Dolabrifera dolabrifera</i> Species of gastropod

Dolabrifera dolabrifera is a species of sea hare, a marine gastropod mollusc in the family Aplysiidae, the sea hares. Dolabrifera dolabrifera, otherwise known as a Warty Seacat. The animal goes by many names, including the common sea hare. The Hawaiian name for Dolabrifera dolabrifera, is Kualakai.

<i>Aplysia fasciata</i> Species of gastropod

Aplysia fasciata, common name the "mottled sea hare", or the "sooty sea hare", is an Atlantic species of sea hare or sea slug, a marine opisthobranch gastropod mollusk in the family Aplysiidae.

<i>Aplysia dactylomela</i> Species of gastropod

Aplysia dactylomela, the spotted sea hare, is a species of large sea slug, a marine opisthobranch gastropod in the family Aplysiidae, the sea hares.

Aplysia extraordinaria, common name the "extraordinary sea hare", is a very large species of sea slug, more specifically a sea hare, a marine opisthobranch gastropod mollusk in the family Aplysiidae, the sea hares.

<i>Aplysia juliana</i> Species of gastropod

Aplysia juliana, the walking sea hare, is a species of sea hare, a marine gastropod in the family Aplysiidae.

<i>Aplysia punctata</i> Species of gastropod

The spotted sea hare is a species of sea slug in the family Aplysiidae, the sea hares. It reaches a length of up to 20 cm (7.9 in) and is found in the northeast Atlantic, ranging from Greenland and Norway to the Mediterranean Sea.

<i>Aplysia vaccaria</i> Species of gastropod

Aplysia vaccaria, also known as the black sea hare and California black sea hare, is a species of extremely large sea slug, a marine, opisthobranch, gastropod mollusk in the family Aplysiidae. It is the largest sea slug species.

<i>Chromodoris orientalis</i> Species of gastropod

Chromodoris orientalis is a species of colourful sea slug, a dorid nudibranch, a marine gastropod mollusc in the family Chromodorididae. Sea slugs are generally very beautifully colored organisms with intense patterns and ranging in sizes. The Chromodoris orientalis specifically is a white sea slug with black spots in no particular pattern with a yellow, orange, or brown in color ring around its whole body and on its gills. There is much discussion on where it is found, what it eats, how it defends itself without a shell, and its reproduction methods. This is all sought after information because there is not much known about these animals.

<i>Aplysia depilans</i> Species of gastropod

Aplysia depilans, the depilatory sea hare, is a species of sea hare or sea slug, a marine opisthobranch gastropod mollusk in the family Aplysiidae. Its name has led to a folk etymology that its consumption caused hair loss.

Aplysia morio, the Atlantic black sea hare or sooty sea hare, is a species of sea slug, a marine gastropod mollusk in the family Aplysiidae, the sea hares. It lives in warm waters in the Caribbean Sea and off the south and southeastern coast of the United States, where it feeds on seaweed.

<span class="mw-page-title-main">Opaline gland</span> Defensive gland in sea hares

Sea hares are gastropods without hard shells, using their specialized ink as their main defensive mechanism instead. Their ink has several purposes, most of which have a chemical basis. For one, the ink serves to cloud the predator's vision as well as halt their senses temporarily. In addition, the chemicals in the ink mimic food. Their skin and digestive tract are toxic to predators as well. They are also seen to change their feeding behaviours in response to averse stimuli.

<i>Aplysia gigantea</i> Species of mollusc in the family Aplysiidae

Aplysia gigantea is a species of sea slug, a shell-less marine gastropod mollusk in the family Aplysiidae. The species was first described in the Journal of the Malacological Society of Australia in 1869. A. gigantea is also known more commonly as the sea hare due to their posterior chemosensory tentacles resembling a hare's ear. A. gigantea is the largest known species in Australia of the opisthobranch genus. The species is known to have toxic effects on terrestrial organisms, particularly domestic dogs. Exposure to this species with dogs has been associated with the development of neurotoxicosis, with symptoms ranging from respiratory distress to tremors, muscle fasciculations, and seizures.

References

  1. ↑ Fischer, P. (1883). Manuel de conchyliologie et de paléontologie conchyliologique fasc. 6. Paris: Savy. pp. 513–608.
  2. ↑ Jörger, K. M.; Stöger, I.; Kano, Y.; Fukuda, H.; Knebelsberger, T.; Schrödl, M. (2010). "On the origin of Acochlidia and other enigmatic euthyneuran gastropods, with implications for the systematics of Heterobranchia". BMC Evolutionary Biology . 10 (1): 323. doi: 10.1186/1471-2148-10-323 . PMC   3087543 . PMID   20973994.
  3. ↑ Gofas, S. (2010). Aplysiomorpha. In: MolluscaBase (2017). Accessed through: World Register of Marine Species at marinespecies.org on 2017-03-30
  4. ↑ Rudman, W.B.; Firminger, P.I., eds. (15 July 2010). "Aplysia vaccaria". The Sea Slug Forum (seaslugforum.net). New South Wales, AU: Australian Museum.
  5. ↑ Barnes, Robert D. (1982). Invertebrate Zoology. Philadelphia, PA: Holt-Saunders International. p. 376. ISBN   0-03-056747-5.
  6. ↑ Ceurstemont, Sandrine (2013-03-28). "New Scientist TV: Sea hares use sticky weapon to cripple predators" . Retrieved 2016-09-30.
  7. ↑ Peterson, Coyote (2016-09-30). "Inked by a Giant Slug! - YouTube". YouTube . Retrieved 2016-09-30.
  8. ↑ Packard, A. (1972). "Cephalopods and Fish: the Limits of Convergence". Biological Reviews. 47 (2): 241–307. doi:10.1111/j.1469-185X.1972.tb00975.x. S2CID   85088231.
  9. ↑ For details of locomotion in the Aplysiomorpha, see Bebbington; Hughes (1973). "Locomotion in Aplysia (Gastropoda, Opisthobranchia)". Journal of Molluscan Studies. 40 (5): 399–405. doi:10.1093/oxfordjournals.mollus.a065237.
  10. ↑ 酱爆海兔的作法
  11. ↑ Edythe McNamee and Jacque Wilson (14 May 2013). "A Nobel Prize with help from sea slugs". CNN. Retrieved 2020-10-31.
  12. ↑ Agranoff, Bernard W.; Cotman, Carl W.; Uhler, Michael D. (1999). "Invertebrate Learning and Memory". Basic Neurochemistry: Molecular, Cellular and Medical Aspects. 6th Edition.
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