Gastrotrichs are a phylum of minute animals, generally less than a
millimetre in length, found in interstitial spaces in sediments (a phylum is
the highest classification of organisms below that of kingdom; other animal
phyla include Molluscs and Arthropods, the Vertebrates only have the status of
a subphylum within the Phylum Chordata, which also includes animals such as Sea
Squirts and Lancets). Their small size meant that they went unnoticed until the
event of microscopy, with the group not being discovered until the 1860s.
Despite this unfamiliarity they seem to be ubiquitous in marine sediments, and
are also often found in non-marine settings.
In a paper published in the journal Zootaxa on 16 April 2015,
Alexander Kieneke of the Deutsches Zentrum für marine Biodiversitätsforschung, AndreasSchmidt-Rhasea of the Centrum für Naturkunde at the Zoologisches Museum in
Hamburg and Rick Hochberg of the University of Massachusetts Lowell describe a
new species of Gastrotrich from the Bahamas.
The new species is placed in the genus Cephalodasys and given the specific name interinsularis, meaning ‘between the islands’, as it was discovered
in sediments from a sandbank between Lee Stocking Island and Norman’s Pond Cay.
Specimens of Cephalodasys interinsularis
measured 471 μm in length (if this seems rather precise it is because Gastrotrichs are eutelic, meaning adults have a fixed number of cells), with a body divided into head, neck and trunk
regions. The head is pair shaped and separated from the neck by a constriction,
the trunk slightly wider than the neck. The body is flat, with a convex ventral
side.
Cephalodasys interinsularis,schematic drawings. Left: Ventral view. Right: Combined dorsal and
internal view. Abbreviations: an, anus; fo, frontal organ; fop, frontal organ
pore; lc, locomotory cilia; me, mature egg; mgp, male genital pore; ov, ovary;
ph, pharynx; pp, pharyngeal pores; sc, sensory cilia; TbA, anterior adhesive
tubes; TbP, posterior adhesive tubes; TbVL, ventrolateral adhesive tubes; te,
testis. Kieneke et al. (2015).
Cephalodasysinter insulariswas found in calcareous biogenic sand (sand made up of shell
fragments) at a depth of two meters, alongside a variety of other Gastrotrich
species, including members of the genera Macrodasys,
Paraturbanella, Tetranchyroderma and Draculiciteria.
It is not known if it is also found in other environments.
Cephalodasys interinsularis, light microscopic. (A) Ventral view showing the adhesive tubes and
locomotorycilia. (B) Horizontal focal plane showing internal organs.
Abbreviations:fo, frontal organ; in, intestine; lc, locomotory cilia; me,
mature egg; ov, ovary; ph, pharynx; pp, pharyngeal pores; TbA, anterior
adhesive tubes; TbP, posterior adhesive tubes; TbVL, ventrolateral adhesive
tubes; te, testis. Kieneke et al. (2015).
See also…
A new species of Gastrotrich from the coast of São Paulo State, Brazil. Gastrotrichs are microscopic animals of uncertain affinities, reaching
at most 3 mm in size, though most species are far smaller. Less than
eight hundred species have been described, living between...
A new species of Gastrotrich from the Atlantic coast of Florida. Gastrotrichs are microscopic animals of uncertain affinities, reaching
at most 3 mm in size, though most species are far smaller. Less than
eight hundred species have been described, living between sediment
particles on the ocean floor, at the bottom of ponds and rivers and in
biofilms covering grains of soil. They have flattened bodies covered in
cilia, with a through gut but...
A new species of Gastrotrich from KwaZulu-Natal. Gastrotrichs are microscopic animals of uncertain affinities, reaching
at most 3 mm in size, though most species are far smaller. Less than
eight...
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