''Berthella caledonica'' 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), ...

sea slug Sea slug is a common name for some Marine biology, marine invertebrates with varying levels of resemblance to terrestrial Slug, slugs. Most creatures known as sea slugs are gastropods, i.e. they are Sea snail, sea snails (marine gastropod moll ...

, a marine

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 ...

mollusk Mollusca is a phylum of protostomic invertebrate animals, whose members are known as molluscs or mollusks (). Around 76,000 extant species of molluscs are recognized, making it the second-largest animal phylum after Arthropoda. The ...

in the family

Pleurobranchidae The Pleurobranchidae are a Taxonomy (biology), taxonomic family (biology), family of sea slugs, marine (ocean), marine gastropod molluscs in the clade Pleurobranchomorpha. Characteristics Species in the family Pleurobranchidae have a promine ...

Distribution

This pleurobranchid was recorded by

Jean Risbec Jean Risbec (1895-1964) was a French zoologist who specialised in studying the insects and Mollusca, Molluscs of New Caledonia, as well as being a taxonomist of the parasitic Hymenoptera. Early years Little is recorded about Risbec's early life b ...

at Orphanage Bay,

Nouméa Nouméa () is the capital and largest city of the French Sui generis collectivity, special collectivity of New Caledonia and is also the largest Francophone city in Oceania. It is situated on a peninsula in the south of New Caledonia's main i ...

New Caledonia New Caledonia ( ; ) is a group of islands in the southwest Pacific Ocean, southwest of Vanuatu and east of Australia. Located from Metropolitan France, it forms a Overseas France#Sui generis collectivity, ''sui generis'' collectivity of t ...

beneath dead coral blocks, with three specimens observed at the time. The species ''Berthella caledonica'' is currently distributed in the

Indo-Pacific The Indo-Pacific is a vast biogeographic region of Earth. In a narrow sense, sometimes known as the Indo-West Pacific or Indo-Pacific Asia, it comprises the tropical waters of the Indian Ocean, the western and central Pacific Ocean, and the ...

region in island territories such as New Caledonia,

Australia Australia, officially the Commonwealth of Australia, is a country comprising mainland Australia, the mainland of the Australia (continent), Australian continent, the island of Tasmania and list of islands of Australia, numerous smaller isl ...

Hawaii Hawaii ( ; ) is an island U.S. state, state of the United States, in the Pacific Ocean about southwest of the U.S. mainland. One of the two Non-contiguous United States, non-contiguous U.S. states (along with Alaska), it is the only sta ...

Okinawa most commonly refers to: * Okinawa Prefecture, Japan's southernmost prefecture * Okinawa Island, the largest island of Okinawa Prefecture * Okinawa Islands, an island group including Okinawa itself * Okinawa (city), the second largest city in th ...

Marshall Islands The Marshall Islands, officially the Republic of the Marshall Islands, is an island country west of the International Date Line and north of the equator in the Micronesia region of the Northwestern Pacific Ocean. The territory consists of 29 c ...

and

Réunion Réunion (; ; ; known as before 1848) is an island in the Indian Ocean that is an overseas departments and regions of France, overseas department and region of France. Part of the Mascarene Islands, it is located approximately east of the isl ...

Habitat

''Berthella caledonica'' is usually a nocturnal species that can often be found in highly to moderately exposed rocky areas. It usually is situated at depths of and during the day-time is often found in pairs under rocks in lagoons and reef flats.

Size

Adults reach up to 50 mm in length; the internal shell measures about 18 mm, is thin, fragile, transparent and pearly, with an oval, slightly concave form and fine growth lines.

Morphology

The broad, smooth mantle is strongly curved and yellowish with dark brown spots. When disturbed, the animal contracts into a tuberculate form and secretes copious black mucus from nasal glands. A central pallial opening is encircled by a pale ring. The head bears two laterally split tentacles, a triangular veil and black eye spots at the tentacle bases. The foot is narrower than the mantle, flared anteriorly and rounded posteriorly. The right side features a bi-lamellar gill and the genital opening. Mantle spines, star-shaped and increasingly numerous toward the center, lie beneath the free margin.

Anatomy

Digestive system

A large buccal bulb with armature, a red muscular zone and a prominent retractor muscle; radula with ~130 rows of 300 unicuspid lateral teeth; paired and unpaired salivary glands; a convoluted oesophagus terminating at a right-sided anus.

Nervous system

A circumenteric nerve collar with paired cerebral, pallial and pedal ganglia; short optic nerves to protruding eyes; extensive suboesophageal commissures.

Reproductive system

Hermaphroditic gland overlaying the liver; ducts leading to albumen gland, uterus, cervix and separate male pathway with a prostate gland and inconspicuous penis; adjacent glaire gland.

References

{{Taxonbar, from=Q61697026 Pleurobranchidae Marine gastropods Molluscs of the Pacific Ocean Molluscs of the Indian Ocean Molluscs of Oceania Gastropods of Oceania Gastropods described in 1928