''Cephalopyge trematoides'' is a
pelagic
The pelagic zone consists of the water column of the open ocean, and can be further divided into regions by depth (as illustrated on the right). The word ''pelagic'' is derived . The pelagic zone can be thought of as an imaginary cylinder or w ...
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
nudibranch
Nudibranchs () are a group of soft-bodied marine gastropod molluscs which shed their shells after their larval stage. They are noted for their often extraordinary colours and striking forms, and they have been given colourful nicknames to mat ...
. A free-swimming
marine gastropod in the family
Phylliroidae. ''Cephalopyge trematoides'' is the only known species in its genus (i.e. the genus is
monotypic
In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unispec ...
).
[
]
Etymology
Cephalopyge is a contraction of cephalus (Greek: κεφαλή , "head") and (πūγή, "behind") referring to the position of the anus close to the head. The species epithet trematoides expresses a likeness to flukes.
Description
''C. trematoides'' grows to 2.5 cm in length. It swims at approximately 12 cm/s, by passing several undulatory waves down its body each second. It is flattened and transparent; its internal organs are visible.[Marine species identification portal]
Cephalopyge
an
Cephalopyge trematoides
Pelagic nudibranchs
Of the approximately 3000 species of nudibranch, the vast majority are benthic
The benthic zone is the ecological region at the lowest level of a body of water such as an ocean, lake, or stream, including the sediment surface and some sub-surface layers. The name comes from ancient Greek, βένθος (bénthos), meaning "t ...
, only a couple are neustonic
Neuston, also known as pleuston, are organisms that live at the surface of the ocean or an estuary, or at the surface of a lake, river or pond. Neuston can live on top of the water surface or may be attached to the underside of the water surface. ...
, and ''C. trematoides'' is very unusual in that it is pelagic. It is estimated to be one of only five planktonic
Plankton are the diverse collection of organisms found in water (or air) that are unable to propel themselves against a current (or wind). The individual organisms constituting plankton are called plankters. In the ocean, they provide a cruc ...
nudibranch species (another epipelagic example is ''Phylliroe bucephala
''Phylliroe bucephala'' is a parasitic species of pelagic nudibranch, a marine gastropod mollusc in the family Phylliroidae.
Biology
This species of nudibranch is transparent with its guts visible through the laterally flattened body. It has a ...
'').[Orso Angulo-Campillo, Gerardo Aceves-Medina and Raymundo Avedaño-Ibarra, ''Holoplanktonic mollusks (Mollusca: Gastropoda) from the Gulf of California, México']
Further information (including photos):
Nudibranch Encyclopedia Kousuke Chibi
(in Japanese)
References
External links
film of ''Cephalopyge'' swimming
{{Taxonbar, from=Q5063321
Phylliroidae
Gastropods described in 1905