Melibe leonina, common name

Common name

A common name of a taxon or organism is a name in general use within a community; it is often contrasted with the scientific name for the same organism...

s the "hooded nudibranch" or the "lion's mane nudibranch", is a species

Species

In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...

 of predatory sea slug

Slug

Slug is a common name that is normally applied to any gastropod mollusc that lacks a shell, has a very reduced shell, or has a small internal shell...

, specifically a nudibranch

Nudibranch

A nudibranch is a member of what is now a taxonomic clade, and what was previously a suborder, of soft-bodied, marine gastropod mollusks which shed their shell after their larval stage. They are noted for their often extraordinary colors and striking forms...

, a marine

Marine (ocean)

Marine is an umbrella term. As an adjective it is usually applicable to things relating to the sea or ocean, such as marine biology, marine ecology and marine geology...

 gastropod mollusk in the family Tethydidae

Tethydidae

Tethydidae is a family of sea slugs, marine gastropod mollusks in the superfamily Tritonioidea.- Taxonomy :This family is within the clade Cladobranchia and has no subfamilies ....

.

Description

This nudibranch is up to 102 mm long, 25 mm wide, and 51 mm across the expanded oral hood.

The body of this nudibranch is translucent. It is usually colorless to pale yellow or green, with opaque brown hepatic diverticula. It has a large expandable oral hood, fringed with sensory tentacle

Tentacle

A tentacle or bothrium is one of usually two or more elongated flexible organs present in animals, especially invertebrates. The term may also refer to the hairs of the leaves of some insectivorous plants. Usually, tentacles are used for feeding, feeling and grasping. Anatomically, they work like...

s, which it opens and throws forward in order to catch food. A single pair of rhinophore

Rhinophore

A rhinophore is one of a pair of club-shaped structures which are the most prominent part of the external head anatomy of a group of sea slugs, marine gastropod opisthobranch mollusks in the order Nudibranchia, the nudibranchs, specifically the dorid nudibranchs.- Etymology :The name relates to the...

s on the hood are rounded and earlike. 4-6 pairs of flat paddle shaped cerata run along its dorsum in two rows.

Melibe leonina exudes a sweet fruity aroma when it is removed from the water, or when numerous individuals are kept together in captivity.

Distribution

This species occurs on the west coast of North America, from Alaska

Alaska

Alaska is the largest state in the United States by area. It is situated in the northwest extremity of the North American continent, with Canada to the east, the Arctic Ocean to the north, and the Pacific Ocean to the west and south, with Russia further west across the Bering Strait...

 to Baja California

Baja California

Baja California officially Estado Libre y Soberano de Baja California is one of the 31 states which, with the Federal District, comprise the 32 Federal Entities of Mexico. It is both the northernmost and westernmost state of Mexico. Before becoming a state in 1953, the area was known as the North...

.

Habitat

Found on eelgrass

Zostera

Zostera is a small genus of widely distributed seagrass, commonly called marine eelgrass or simply eelgrass . The genus Zostera contains sixteen species.-Ecology:Zostera is found on sandy substrates or in estuaries submerged or partially floating...

 and other seaweeds near low tide and below, and in kelp forest

Kelp forest

Kelp forests are underwater areas with a high density of kelp. They are recognized as one of the most productive and dynamic ecosystems on Earth. Smaller areas of anchored kelp are called kelp beds....

 in deeper water.

Feeding habits

Melibe leonina is carnivorous and hunts for food, while attached to grasses, by extending its oral hood out and downward like a net. When the ventral surface of the hood contacts a small animal, the hood rapidly closes and the fringing tentacles overlap, holding in the prey then forcing the whole animal into the mouth. Prey include amphipods, copepod

Copepod

Copepods are a group of small crustaceans found in the sea and nearly every freshwater habitat. Some species are planktonic , some are benthic , and some continental species may live in limno-terrestrial habitats and other wet terrestrial places, such as swamps, under leaf fall in wet forests,...

s, mysids

Mysidae

Mysidae is a family of crustaceans in the order Mysida or mysid shrimps. Six sub-families are recognised:* Boreomysinae Holt & W. M. Tattersall, 1905a* Siriellinae Norman, 1892* Rhopalophthalminae Hansen, 1910* Gastrosaccinae Norman, 1892...

, other small crustacean

Crustacean

Crustaceans form a very large group of arthropods, usually treated as a subphylum, which includes such familiar animals as crabs, lobsters, crayfish, shrimp, krill and barnacles. The 50,000 described species range in size from Stygotantulus stocki at , to the Japanese spider crab with a leg span...

s, small mollusks, small jellyfish

Jellyfish

Jellyfish are free-swimming members of the phylum Cnidaria. Medusa is another word for jellyfish, and refers to any free-swimming jellyfish stages in the phylum Cnidaria...

 and ctenophore

Ctenophore

The Ctenophora are a phylum of animals that live in marine waters worldwide. Their most distinctive feature is the "combs", groups of cilia that they use for swimming, and they are the largest animals that swim by means of cilia – adults of various species range from a few millimeters to in size...

s, larvae of other invertebrates and in some cases small fish.

Life cycle

Like most other sea slugs, Melibe leonina is a hermaphrodite

Hermaphrodite

In biology, a hermaphrodite is an organism that has reproductive organs normally associated with both male and female sexes.Many taxonomic groups of animals do not have separate sexes. In these groups, hermaphroditism is a normal condition, enabling a form of sexual reproduction in which both...

. They apparently live about one year, reciprocally fertilize one another, lay their eggs and die. Eggs are attached to kelp and eelgrass in long, wide yellow or cream-colored ribbons which form tight coils or wavy folds.

Predators

Predators may include fish, kelp dwelling crabs and sea stars, but when disturbed Melibe leonina has the ability to autotomize (shed) its cerata. This will hopefully lead the would-be attacker away as the discarded appendages float off, or at least cause a distraction long enough for the sea slug to make an escape.

When harassed or dislodged, Melibe leonina is capable of swimming. It uses rhythmic lateral-bending movements, and can sometime travel long distances across open water. The upside-down, side-to-side thrashing motion may look awkward, but it is a complex series of movements which has been studied extensively.

Further reading

• Agersborg H. P. K. (1923). "The Morphology of the Nudibranchiate Mollusc Melibe (syn. Chioraera) leonina (Gould)". Quarterly journal of microscopical science 67: 507-592.
• Agersborg H. P. K. (1923). "A CRITIQUE ON PROFESSOR HAROLD HEATH'S CHIORAERA DALLI, WITH SPECIAL REFERENCE TO THE USE OF THE FOOT IN THE NUDIBRANCHIATE M0LLUSK, MELIBE LEONINA GOULD". The Nautilus 36(3): 86-96.