''Paranemertes peregrina'' is a species of

Nemertea Nemertea is a phylum of animals also known as ribbon worms or proboscis worms, consisting of about 1300 known species. Most ribbon worms are very slim, usually only a few millimeters wide, although a few have relatively short but wide bodies. ...

, or ribbon worm, in the family

Neesiidae ''Neesiidae'' is a family of worms belonging to the order Monostilifera Monostilifera is a suborder of nemertean worms belonging to the class Hoplonemertea (formerly Enopla Enopla is one of the classes of the worm phylum Nemertea, charac ...

Description

''P. peregrina'' is usually dark dorsally, with a brown or purple coloration. It appears peach-colored due to its lighter ventral coloration. Their distinctive external features and spiral-shaped stylets make them easily recognizable. These stylets feature spirally wrapped grooves on their shafts that grow within vacuoles. They, like annelids and mollusks, have spiral cleavage and trochophore larvae. In its developmental stage, ''P. peregrina'' progresses from swimming to crawling in around ten days. Nemerteans often have an Anoplan or Enoplan morphology, with P. peregrina having an Enoplan morphology.

Distribution

They are observed in the

Pacific Ocean The Pacific Ocean is the largest and deepest of Earth's five Borders of the oceans, oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean, or, depending on the definition, to Antarctica in the south, and is ...

from the

Aleutian Islands The Aleutian Islands ( ; ; , "land of the Aleuts"; possibly from the Chukchi language, Chukchi ''aliat'', or "island")—also called the Aleut Islands, Aleutic Islands, or, before Alaska Purchase, 1867, the Catherine Archipelago—are a chain ...

Ensenada, Baja California Ensenada ("inlet") is a city in Ensenada Municipality, Baja California, situated on the Pacific Coast of Mexico. Located on Bahía de Todos Santos, the city had a population of 279,765 in 2018, making it the List of cities in Baja California, th ...

. This species can be found in intertidal habitats characterized by both muddy and rocky bays.

Ecology

The species feeds exclusively on live or dead

polychaete Polychaeta () is a paraphyletic class of generally marine Annelid, annelid worms, common name, commonly called bristle worms or polychaetes (). Each body segment has a pair of fleshy protrusions called parapodia that bear many bristles, called c ...

s. Digestion occurs both within and outside of cells. Food is broken down in an acidic environment by specific cells using enzymes such as peptidases, carbohydrates, and lipases. After the meal has been partially digested, it is taken by cells and thoroughly broken down with more enzymes, causing the pH to shift from acidic to alkaline. The worm's movements across intertidal flats in search of prey inspired the specific name "''peregrina''". The feeding process starts when its head recoils upon making contact with prey, as the species does not locate prey through distance chemoreception but rather through direct contact. It then involves the exposure of the

proboscis A proboscis () is an elongated appendage from the head of an animal, either a vertebrate or an invertebrate. In invertebrates, the term usually refers to tubular arthropod mouthparts, mouthparts used for feeding and sucking. In vertebrates, a pr ...

, which wraps around the prey. This action results in the temporary paralysis or death of the prey. Finally, the prey is swallowed by sucking through the help of muscles surrounding the mouth. It subsequently releases waste within a time frame ranging from 12 to 33 hours after consuming food. The feeding process lasts for seven to eight minutes upon successful contact. Following this, ''P. peregrina'' retraces its path to the burrow, relying on the mucus trail it left behind.

References

{{Taxonbar, from=Q2622437 Wikipedia Student Program Nemerteans