''Thysanozoon nigropapillosum'' is a species of
polyclad flatworms belonging to the family
Pseudocerotidae. Some common names include gold-speckled flatworm, marine flatworm, yellow papillae flatworm, yellow-spotted flatworm, and yellow-spotted polyclad flatworm.
Description
''Thysanozoon nigropapillosum'' has a long body and broad shape. They grow up to .
The dorsal surface is deep black and covered with numerous yellow-tipped papillae varying in size. The ventral surface is dark brown. The outer margin of the body is slightly wavy and bordered in opaque white. They have small, ear-like pseudotentacles in the middle of the anterior end.
They swim by propelling themselves through the water with a rhythmic undulating motion of the body.
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Distribution
This species is widespread in the tropical Indo-Pacific.
Biology
''Thysanozoon nigropapillosum'' is quite common along the external reef in the shallow sub-tidal zone. It can swim by undulating and rhythmically contracting the body margins. It feeds on tunicate
A tunicate is a marine invertebrate animal, a member of the subphylum Tunicata (). It is part of the Chordata, a phylum which includes all animals with dorsal nerve cords and notochords (including vertebrates). The subphylum was at one time ...
s, using its mouth and large pharynx to engulf '' Didemnum'' spp., and later regurgitates food pellets containing the calcareous spicules present in their tunics. Polyclad flatworms are hermaphrodites, with each one of a pair of flatworms trying to inseminate the other. Transfer of sperm may be by hypodermic insemination
Traumatic insemination, also known as hypodermic insemination, is the mating practice in some species of invertebrates in which the male pierces the female's abdomen with his aedeagus and injects his sperm through the wound into her abdominal cav ...
, but this is made difficult in this species by the presence of the papillae, and dermal impregnation often occurs. This involves sperm entering the body directly after being placed in the marginal region of the skin. Such dermal insemination is facilitated by the fact that the flatworm has two penises which are strengthened by the presence of rhabdite
Rhabdites (from Greek, ''rhabdos'', rod) are rodlike structures in the cells of the epidermis
The epidermis is the outermost of the three layers that comprise the skin, the inner layers being the dermis and hypodermis. The epidermis layer pr ...
s, and these can grip the margin of the partner and keep hold, even while the recipient is swimming.
References
External links
World Database of Marine Species
Worms
Zipcodezoo
Gwannon
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{{Taxonbar, from=Q7799832
Turbellaria
Animals described in 1959