''Phoronis ovalis'' is a

species In biology, a species is the basic unit of Taxonomy (biology), 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 ...

of marine horseshoe worm in the

phylum In biology, a phylum (; plural: phyla) is a level of classification or taxonomic rank below kingdom and above class. Traditionally, in botany the term division has been used instead of phylum, although the International Code of Nomenclatu ...

Phoronid Phoronids (scientific name Phoronida, sometimes called horseshoe worms) are a small phylum of marine animals that filter-feed with a lophophore (a "crown" of tentacles), and build upright tubes of chitin to support and protect their soft bodies. ...

a. It is found in shallow waters in the northeastern Atlantic Ocean, the southeastern Atlantic Ocean, Argentina, and other scattered locations worldwide. These worms secrete a tube into which they can retreat, and burrow into the shells of

molluscs Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as molluscs or mollusks (). Around 85,000 extant species of molluscs are recognized. The number of fossil species is esti ...

Description

''Phoronis ovalis'' is a small horseshoe worm growing to an extended length of and a diameter of . It exhibits many primitive traits. The

lophophore The lophophore () is a characteristic feeding organ possessed by four major groups of animals: the Brachiopoda, Bryozoa, Hyolitha, and Phoronida, which collectively constitute the protostome group Lophophorata.hermaphrodite In reproductive biology, a hermaphrodite () is an organism that has both kinds of reproductive organs and can produce both gametes associated with male and female sexes. Many taxonomic groups of animals (mostly invertebrates) do not have ...

, and the

embryo An embryo is an initial stage of development of a multicellular organism. In organisms that reproduce sexually, embryonic development is the part of the life cycle that begins just after fertilization of the female egg cell by the male sperm ...

s are brooded in the tube. Asexual reproduction can also take place, either by

budding Budding or blastogenesis is a type of asexual reproduction in which a new organism develops from an outgrowth or bud due to cell division at one particular site. For example, the small bulb-like projection coming out from the yeast cell is kno ...

or by

transverse fission Strobilisation or transverse fission is a form of asexual reproduction consisting of the spontaneous transverse segmentation of the body. It is observed in certain cnidarians and helminths. This mode of reproduction is characterized by high offspr ...

. The lophophore is used for feeding and for gas exchange. Under adverse conditions, the lophophore is readily autotomised; the animal can regenerate its lophophore and the shed lophophore can grow a new body. In 2010 it was reported that ''Phoronis ovalis'' was present in beds of molluscs off the coast of Namibia, it having not previously been recorded in Africa. The brown mussel (''

Perna perna ''Perna perna'', the brown mussel, is an economically important mussel, a bivalve mollusc belonging to the family Mytilidae. It is harvested as a food source but is also known to harbor toxins and cause damage to marine structures. It is native ...

'') was the mollusc most frequently found acting as a host, and in one mussel bed, 99% of the mussels exhibited the boreholes made by the horseshoe worm. Other hosts included three other species of

bivalve molluscs Bivalvia (), in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class of marine and freshwater molluscs that have laterally compressed bodies enclosed by a shell consisting of two hinged parts. As a group, biva ...

, four species of gastropod mollusc and one

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 erosive ...

species.

References

{{Taxonbar, from=Q2049875 Phoronids Animals described in 1856