Chelidonura hirundinina is a species of small and colorful aglajid 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...

, a shell-less opisthobranch gastropod mollusk in the family Aglajidae

Aglajidae

Aglajidae is a family of often colorful, medium-sized, sea slugs, marine opisthobranch gastropod mollusks. These are not nudibranchs; instead they are headshield slugs, in the clade Cephalaspidea.-Genera:...

. Despite its colorful appearance, this is not a species of 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...

; it is a cephalaspidean

Cephalaspidea

The suborder Cephalaspidea, also known as the headshield slugs and bubble snails, is a clade of sea slugs and bubble snails, marine gastropod mollusks within the larger clade Euopisthobranchia....

, a headshield slug. This is a tropical species which lives in the western Indo-Pacific

Indo-Pacific

The Indo-Pacific is a biogeographic region of the Earth's seas, comprising the tropical waters of the Indian Ocean, the western and central Pacific Ocean, and the seas connecting the two in the general area of Indonesia...

, and also in the Caribbean Sea

Caribbean Sea

The Caribbean Sea is a sea of the Atlantic Ocean located in the tropics of the Western hemisphere. It is bounded by Mexico and Central America to the west and southwest, to the north by the Greater Antilles, and to the east by the Lesser Antilles....

.

Description

This species has a maximum size of 40 mm, but is often smaller than that. The background color can be red, orange, dark brown, or black. There are blue, black, and orange stripes on the body, and there is a white marking towards the posterior end of the animal.

The two rather long "tails" at the end of the animal are characteristic of the genus Chelidonura. The specific epithet hirundinina is Latin, meaning "little swallow

Swallow

The swallows and martins are a group of passerine birds in the family Hirundinidae which are characterised by their adaptation to aerial feeding...

", in reference to this swallow-tailed appearance.

Books

• Valdez, Hamann, Berhrens & DuPont, 2006, Caribbean sea slugs: a field guide to the opisthobranch mollusks from the tropical northwestern Atlantic, Sea Challengers Natural History Books, Washington