Aplysia vaccaria

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Aplysia vaccaria
Aplysia vaccaria Rades sea.jpg
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Mollusca
Class: Gastropoda
Subclass: Heterobranchia
Clade: Euopisthobranchia
Clade: Anaspidea
Superfamily: Aplysioidea
Family: Aplysiidae
Genus: Aplysia
Species:
A. vaccaria
Binomial name
Aplysia vaccaria
Winkler, 1955

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. [1] It is the largest sea slug species. [2]

Contents

Distribution

This sea hare species lives in the northeast Pacific Ocean off California, United States, and Baja California, Mexico, including the Gulf of California. [3]

Description

The black sea hare can grow to be very large; the longest recorded specimen measured 99 cm (39 in) when crawling (thus fully extended), and weighed nearly 14 kg (31 lb). [3]

Unlike Aplysia californica , the body of this species is relatively firm, and the parapodia are joined behind the siphon. [3]

Unlike many other members of the same family and genus, this species is incapable of producing ink.

Feeding habits

All Aplysia species are herbivorous. This species eats brown seaweeds and kelp, which give the animal its typically very dark coloration.[ citation needed ]

Lifecycle and behavior

Aplysia vaccaria has a lifecycle of one year. [4] They grow very quickly, at an average rate of 4.9 g/day. [5] This high rate of growth allows A. vaccaria to become the largest known species of sea slug. [2] It is a herbivore that feeds on brown algae, but its close relative A. californica feeds almost exclusively on red algae. [6] This difference in food sources likely minimizes competition between the two species, which share much of the same habitat. A. vaccaria is found in the intertidal and upper-subtidal zone, meaning that it can survive exposure to air while the tide is out. It is rarely preyed upon by other organisms, which has made it the subject of various experiments testing for a secreted biotoxin that discourages predation. [6] The large size of A. vaccaria also contributes to its lack of predators. It is simply too big for many predators to attack or consume.

Mating habits

Aplysia vaccaria is a simultaneous hermaphrodite; [4] it has both male and female sex organs that are able to contribute to sexual reproduction at the same time, which is distinct from nonsimultaneous (or sequential) hermaphrodites, which only have one sex organ present or functional at any one time. Being simultaneously hermaphroditic is advantageous because any two individuals are able to reproduce with one another, which facilitates them finding mates. Despite having both sex organs functional during reproduction, only one Aplysia vaccaria acts as a sperm donor during the mating encounter, [4] which is determined by the relative sizes of the two individuals. The smaller individual most often acts as the sperm donor, while the larger individual acts as the sperm recipient. [4] Because the reproductive role of A. vaccaria is dependent on the relative sizes between a mating pair, one individual can act as both a sperm donor and a sperm recipient during a mating season. Larger individuals are suggested to be preferentially selected for mating, and they act as the sperm recipient to avoid the competition present between smaller individuals to be sperm donors. This mechanism of size-assortative mating is common among gastropods.

Production of defense substances

Aplysia vaccaria can be safely handled by humans Aplysia vaccaria 248938025.jpg
Aplysia vaccaria can be safely handled by humans

The scarcity of natural predators for sea hares has long suggested to scientists that some kind of toxin must be produced to discourage predation. [4] Unlike most members of its family, A. vaccaria is incapable of producing ink. The absence of this defense mechanism while maintaining a very low level of predation further suggests that it is protected by a secreted toxin effective enough that the production of ink for defense purposes was no longer evolutionarily beneficial. Sea hares form their toxins from compounds they receive from their foods. [7] This is significant because the type of algae the sea hare eats determines the toxins it produces. [6] A. vaccaria primarily feeds on brown algae, so its toxins are derived from this source and are distinct from sea hares such as A. californica, which feeds on red algae. Food sources also determine the color of the sea hare, which explains why A. vaccaria appears black or dark brown while A. californica appears red. [6] To discourage predation by fish, brown algae produce the toxin acetoxycrenulide. [6] During digestion, A. vaccaria extracts this compound and allows it to accumulate in its tissue. Because acetoxycrenulide is highly toxic to fish, its presence in this slug is sufficient to discourage predation. [7]

Related Research Articles

<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">Anaspidea</span> Clade of gastropods

The clade Anaspidea, commonly known as sea hares, 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.

<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 entirely lost their shells or have seemingly lost their shells due to having a significantly reduced or internal shell. The name "sea slug" is often applied to nudibranchs and a paraphyletic set of other marine gastropods without apparent shells.

<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.

<i>Aplysia</i> Genus of sea slugs

Aplysia is a genus of medium-sized to extremely large sea slugs, specifically sea hares, which are a kind of marine gastropod mollusk.

<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>Elysia timida</i> Species of gastropod

Elysia timida is a species of sacoglossan sea slug, a marine opisthobranch gastropod mollusk. Found in the Mediterranean and nearby parts of the Atlantic, it is herbivorous, feeding on various algae in shallow water.

<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.

<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>Condylactis gigantea</i> Species of sea anemone

Condylactis gigantea is a tropical species of ball anemone that is found in shallow reefs and other shallow inshore areas in the Caribbean Sea – more specifically the West Indies – and the western Atlantic Ocean including southern Florida through the Florida Keys. It is also commonly known as: giant Caribbean sea anemone, giant golden anemone, condylactis anemone, Haitian anemone, pink-tipped anemone, purple-tipped anemone, and Florida condy. This species can easily be seen growing in lagoons or in inner reefs as either individuals or loose groups, but never as colonies. They are often used as a model organism along with others in their genus for facultative symbiosis with monocellular algae.

<span class="mw-page-title-main">Chemical defense</span>

Chemical defense is a strategy employed by many organisms to avoid consumption by producing toxic or repellent metabolites or chemical warnings which incite defensive behavioral changes. The production of defensive chemicals occurs in plants, fungi, and bacteria, as well as invertebrate and vertebrate animals. The class of chemicals produced by organisms that are considered defensive may be considered in a strict sense to only apply to those aiding an organism in escaping herbivory or predation. However, the distinction between types of chemical interaction is subjective and defensive chemicals may also be considered to protect against reduced fitness by pests, parasites, and competitors. Repellent rather than toxic metabolites are allomones, a sub category signaling metabolites known as semiochemicals. Many chemicals used for defensive purposes are secondary metabolites derived from primary metabolites which serve a physiological purpose in the organism. Secondary metabolites produced by plants are consumed and sequestered by a variety of arthropods and, in turn, toxins found in some amphibians, snakes, and even birds can be traced back to arthropod prey. There are a variety of special cases for considering mammalian antipredatory adaptations as chemical defenses as well.

<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.

<span class="mw-page-title-main">Phagomimicry</span>

Phagomimicry is a defensive behaviour of sea hares, in which the animal ejects a mixture of chemicals, which mimic food, and overwhelm the senses of their predator, giving the sea hare a chance to escape. The typical defence response of the sea hare to a predator is to release two chemicals - ink from the ink gland and opaline from the opaline gland. While ink creates a dark, diffuse cloud in the water which disrupts the sensory perception of the predator by acting as a smokescreen and as a decoy, the opaline, which affects the senses dealing with feeding, causes the predator to instinctively attack the cloud of chemicals as if it were indeed food. This ink is able to mimic food by having a high concentration of amino acids and other compounds that are normally found in food, and the attack behaviour of the predator allows the sea-hares the opportunity to escape.

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>Phestilla minor</i> Species of gastropod

Phestilla minor is a species of sea slug in the Trichechidae family. It is a type of aeolid nudibranch under the Aeolidina suborder. Phestilla minor is a benthic sea slug that is a very small, slow-moving organism found in marine habitats all over the world.

<span class="mw-page-title-main">Aplysioviolin</span> Chemical compound

Aplysioviolin is a purple-colored molecule secreted by sea hares of the genera Aplysia and Dolabella to deter predators. Aplysioviolin is a chemodeterrent, serving to dispel predators on olfactory and gustatory levels as well as by temporarily blinding predators with the molecule's dark color. Aplysioviolin is an important component of secreted ink and is strongly implicated in the sea hares' predatory escape mechanism. While the ink mixture as a whole may produce dangerous hydrogen peroxide and is relatively acidic, the aplysioviolin component alone has not been shown to produce human toxicity.

<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.

<i>Thuridilla vataae</i> Species of sea slug gastropod

Thuridilla vataae is a species of sacoglossan sea slug, a shell-less marine opisthobranch gastropod mollusc in the family Plakobranchidae. It is native to the tropical Indo-Pacific. It was first described by the French zoologist Jean Risbec in 1928; its specific name refers to the Bay of Anse Vata, just south of Nouméa, New Caledonia, where the type specimen was collected.

References

  1. Bouchet, P. (2011). Aplysia vaccaria Winkler, 1955. Accessed through: World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxdetails&id=568031 on 2012-03-31
  2. 1 2 "California Black Sea Hare, Aplysia vaccaria". nathistoc.bio.uci.edu. Retrieved 2019-01-04.
  3. 1 2 3 Sea Slugs: Aplysia vaccaria. Retrieved 25 February 2015.
  4. 1 2 3 4 5 Angeloni, L.; Bradbury, J. (1999). "Body size influences mating strategies in a simultaneously hermaphroditic sea slug, Aplysia vaccaria". Ethology Ecology & Evolution. 11 (2): 187–195. doi:10.1080/08927014.1999.9522836. ISSN   0394-9370.
  5. Angeloni, Lisa, Jack Bradbury, and Alexis Chaine. "Growth, seasonality, and dispersion of a population of Aplysia vaccaria Winkler 1955" Veliger–Berkeley 42 (1999): 1–9.
  6. 1 2 3 4 5 Midland, Sharon L.; Wing, Richard M.; Sims, James J. (1983). "New crenulides from the sea hare, Aplysia vaccaria". The Journal of Organic Chemistry. 48 (11): 1906–1909. doi:10.1021/jo00159a026. ISSN   0022-3263.
  7. 1 2 Winkler, Lindsay R. (1961) "Preliminary tests of the toxin extracted from California sea hares of the genus Aplysia" Pacific Science. 15: 211-214