''Procerodes littoralis'' is a species of
triclad
A planarian is one of the many flatworms of the traditional class Turbellaria. It usually describes free-living flatworms of the order Tricladida (triclads), although this common name is also used for a wide number of free-living platyhelmint ...
flatworm
The flatworms, flat worms, Platyhelminthes, or platyhelminths (from the Greek πλατύ, ''platy'', meaning "flat" and ἕλμινς (root: ἑλμινθ-), ''helminth-'', meaning "worm") are a phylum of relatively simple bilaterian, unsegme ...
widely distributed on the shores of northwestern Europe and on the east coast of North America from Newfoundland northwards.
Description
''Procerodes littoralis'' is a small flatworm with a maximum length of and width of , but it is usually smaller than this. It has a fairly wide head with two distinctive marginal tentacles with a pair of eyes behind them. The neck region is slightly narrower and the body is plump and bottle-shaped. The dorsal surface is greyish or olive-brown and the internal organs are sometimes visible through the cuticle. The eyes are surrounded by pale patches which are separated by a slightly darker stripe.
Distribution and habitat
''Procerodes littoralis'' is found in the temperate northwestern Atlantic Ocean, on the European coastline, and on the coast of North America from Newfoundland northwards. It is common round the coasts of Britain on the upper and middle shores where it is the most common marine flatworm.
[ It is tolerant of wide fluctuations in ]salinity
Salinity () is the saltiness or amount of salt dissolved in a body of water, called saline water (see also soil salinity). It is usually measured in g/L or g/kg (grams of salt per liter/kilogram of water; the latter is dimensionless and equal ...
, and is often being plentiful in areas where freshwater streams flow across the beach; it conceals itself under boulders and stones, on shingle and sand.[
]
Ecology
The chosen habitat of this species is streambeds on the upper shore. Here it is exposed for about eight hours in every tidal cycle to fresh water and for about four hours to salt water. It can survive in both these environments but is inactive at the two extremes of 0 psu and 44 psu. At high tide it tends to gather under large stones where it is protected from wave action while at low tide it tends to burrow down to the base of the gravel where there is probably some residual salinity. This is where it feeds on detritus and such small invertebrates as oligochaete
Oligochaeta () is a subclass of animals in the phylum Annelida, which is made up of many types of aquatic and terrestrial worms, including all of the various earthworms. Specifically, oligochaetes comprise the terrestrial megadrile earthworm ...
s and marine isopods
Isopoda is an order of crustaceans that includes woodlice and their relatives. Isopods live in the sea, in fresh water, or on land. All have rigid, segmented exoskeletons, two pairs of antennae, seven pairs of jointed limbs on the thorax, an ...
, including '' Jaera albifrons'' and '' Jaera nordmanni''.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 fertilisation is internal. Batches of about five eggs are laid in oval capsules about in diameter which are glued to the underside of stones. The eggs undergo direct development Marine larval ecology is the study of the factors influencing dispersing larvae, which many marine invertebrates and fishes have. Marine animals with a larva typically release many larvae into the water column, where the larvae develop before met ...
, hatching directly into miniature adults long.
References
{{Taxonbar, from=Q2053279
Maricola
Animals described in 1768
Taxa named by Hans Strøm
Fauna of the Atlantic Ocean