Mud Nemertean

How to Distinguish from Similar Species: Emplectonema purpuratum may also be purple or brownish-purple but it is much longer and often has light brown specks. Paranemertes sanjuanensis is similar in structure but is colored pale orange to flesh color.

Biology/Natural History: This common species feeds on polychaetes, especially nereids, at low tide. At high tide it remains mostly under cover but it is often seen crawling along rocks or mud, hunting during early-morning or nighttime low tides. It can swallow prey slightly larger than itself. In Washington a primary prey species is the small nereid Platynereis bicanaliculata which builds small tubes on Ulva, while in Alaska Nereis vexillosa is common prey. Many Nereids show strong escape behavior after coming in contact with P. peregrina. It seems to need to actually physically contact prey in order to detect its presence. On contact with nereid prey, P. peregrina pulls its head back and everts its light-colored proboscis, which wraps around the prey. The prey is soon paralyzed, probably by the alkaloid neurotoxin anabaseine from the stylet or from posterior proboscis glands. P. peregrina then swallows the nereid. After feeding it follows its own slime trail back to its burrow. It eats about one prey worm per day and seems to reuse its stylet on multiple prey. It can readily be induced to attack nereid worms in a laboratory dish. It sometimes also preys on nephtyid, syllid, or spionid worms as well. Exposure to fresh water may trigger eversion of the proboscis. In many populations, many more females are found than males. Spawning is mostly in spring and summer but may extend through the fall and into winter. Populations in any one place tend to spawn within about a month of each other. The orange-brown eggs are deposited singly or in gelatinous clusters and hatch in about 3 days. Worms live about 1 1/2 years. Some evidence suggests that anabaseine may be useful against Alzheimer's disease in humans.

Under rocks and under algae on wave-swept shores; or in the Pacific Northwest most commonly within or on muddy sediments or under stones in quieter environments.

Geographical Range: Japan; Kamchatka; Aleutian Islands, Alaska to Ensenada, Baja California, Mexico

Depth Range: Mid and low intertidal; shallow subtidal

As a member of Class Enopla, the mouth and proboscis pore are united and at the anterior tip of the head and the proboscis is armed with a stylet. In P. peregrina the stylet has a substantial shaft with helical grooves and ridges. The proboscis sheath is more than 1/5 the length of the body. Typically there are 2-3 sacs of reserve stylets, with about 4 stylets in each sac. Has numerous ocelli, but these do not extend behind the cerebral ganglia. It does not have a statocyst. The species does not usually live commensally with other species such as crustaceans or clams. Dorsal surface is brown to purplish-brown and the ventral surface is yellow to creamy white. There is a lighter dorsal band near the borders and back of the head which extends across the posterior groups of ocelli. The tail may be pointed. Up to over 25 cm long but usually 6-15 cm.