''Ceriantheopsis americana'' is a

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

tube-dwelling anemone Tube-dwelling anemones or ceriantharians look very similar to sea anemones but belong to an entirely different class of anthozoans. They are solitary, living buried in soft sediments. Tube anemones live inside and can withdraw into tubes, which ...

in the

family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...

Cerianthidae Cerianthidae is a family of tube-dwelling anemones in the order Spirularia of the subclass Ceriantharia. Genera The World Register of Marine Species includes the following genera in the family: * ''Anthoactis'' Leloup, 1932 * ''Apiactis'' Bened ...

. It is a burrowing species and lives in deep sand or muddy sand in a long slender tube that it creates.

Description

''Ceriantheopsis americana'' is a large tube-dwelling anemone. The crown of tentacles can have a diameter of up to and project for 10 cm above the surface of the sediment. This anemone has a slender, elongated body and creates a tough, felted, leathery tube to line its burrow, using discharged

cnidocyte A cnidocyte (also known as a cnidoblast or nematocyte) is an explosive cell containing one large secretory organelle called a cnidocyst (also known as a cnida () or nematocyst) that can deliver a sting to other organisms. The presence of this ce ...

s stuck together with mucus and incorporating sand grains on the outer surface. The tube is orientated vertically in the sediment, with a maximum length of about . There is often a connecting short lateral tube branching off near the upper end. The top entrance is somewhat elastic and is up to in diameter, and the tube narrows towards the base.

Distribution and habitat

''Ceriantheopsis americana'' is native to the western Atlantic Ocean where it occurs between

Maine Maine () is a state in the New England and Northeastern regions of the United States. It borders New Hampshire to the west, the Gulf of Maine to the southeast, and the Canadian provinces of New Brunswick and Quebec to the northeast and north ...

and

Cape Hatteras Cape Hatteras is a cape located at a pronounced bend in Hatteras Island, one of the barrier islands of North Carolina. Long stretches of beach, sand dunes, marshes, and maritime forests create a unique environment where wind and waves shape ...

in the United States. It occurs in soft substrates in the

sublittoral zone The neritic zone (or sublittoral zone) is the relatively shallow part of the ocean above the drop-off of the continental shelf, approximately in depth. From the point of view of marine biology it forms a relatively stable and well-illuminated ...

and the lowest parts of the

littoral zone The littoral zone or nearshore is the part of a sea, lake, or river that is close to the shore. In coastal ecology, the littoral zone includes the intertidal zone extending from the high water mark (which is rarely inundated), to coastal areas ...

in sheltered areas, being most common just below the low tide mark.

Ecology

During the day the anemone retreats into its tube and closes the entrance. As evening approaches and at night, it extends its crown of tentacles and spreads the longer tentacles around the tube entrance. It is a predator and mostly feeds on calenoid copepods, which are

plankton Plankton are the diverse collection of organisms found in Hydrosphere, water (or atmosphere, air) that are unable to propel themselves against a Ocean current, current (or wind). The individual organisms constituting plankton are called plankt ...

ic, and harpacticoid copepods, which are bottom-dwellers. It also consumes

barnacle A barnacle is a type of arthropod constituting the subclass Cirripedia in the subphylum Crustacea, and is hence related to crabs and lobsters. Barnacles are exclusively marine, and tend to live in shallow and tidal waters, typically in eros ...

amphipods Amphipoda is an order of malacostracan crustaceans with no carapace and generally with laterally compressed bodies. Amphipods range in size from and are mostly detritivores or scavengers. There are more than 9,900 amphipod species so far descri ...

and gastropod molluscs. ''Ceriantheopsis americana'' is plentiful in

Narragansett Bay Narragansett Bay is a bay and estuary on the north side of Rhode Island Sound covering , of which is in Rhode Island. The bay forms New England's largest estuary, which functions as an expansive natural harbor and includes a small archipelago. Sma ...

, Rhode Island but was overlooked for a long time, probably because of its habit of retreating into its burrow when disturbed. In this location it appears to no longer be present after mid August but then reappears in mid-October. It seems likely that its apparent disappearance is due to it burrowing more deeply into the substrate in that period in order to avoid being eaten by

scup The scup (''Stenotomus chrysops'') is a fish which occurs primarily in the Atlantic from Massachusetts to South Carolina. Along with many other fish of the family Sparidae, it is also commonly known as porgy. Scup grow as large as 18 in (450&n ...

(''Stenotomus chrysops'') when the schools of young fish move inshore. When the fish depart again in the fall, the anemone reappears, at similar sizes and densities to its situation before. Examination of the stomach contents of young scup reinforce this hypothesis.

References

{{Taxonbar, from=Q4004579 Cerianthidae Animals described in 1864