Creature of the week
Chaetopterus – parchment worm
Chaetopterus variopedatus
Origin of name – Greek words (khaite =long hair or bristle) + (pteron = wing eg; helic–opter!)
Maximum 150 mm long.
After Easterly storms,
thousands of these tough,
twisted, parchment
casings are washed ashore.
The washed up rock in the left
picture was capsized, revealing
.the type of natural habitat of
chaetopterus.
The lower picture shows the tube (chimney) at the right extremity which
would have been sucking clear water into the animal.
Chaetopterus or the parchment worm is one of the most bizarly specialised animals belonging to
the marine polychaete ( means many bristly legs) family of worms. It lives in a tube it constructs in
sediments and attaches it to a rocky surface. Parchment tube worms are filter feeders and spend their
adult lives in their tubes. They are planktonic in their juvenile forms,
Description:The worm has spines along its
body segments that are modified for
tunneling into the sandy substrate to create
the u-shaped tube within which it lives.
The tubes form tunnels lined with mucous.
Each parchment tube ends with a chimney
of parchment that juts above the substrate.
The tubes can be as long as150mm and up
to 12 mm in diameter at the widest portion.
The worms are unique among the polychaet
worms in that the highly specialized legs
each side of the mid-segments of its body
are used in its filter feeding regime. The worm feeds by using modified structures on its upper body
segments (notopodia) that create mucus nets to trap food passed through the net. A flow of water
containing plankton and organic debris is created by "circular flaps"
on three middle segments that work like pistons against the tunnel
walls so creating suction that draws water through the living tube.
The water is drawn in through the anterior end and expelled through
the posterior end, passing through the fine mesh of the mucus bag
where food particles get trapped. The mucus bag is later rolled up
and passed by a conveyor belt of whipping hairs in the ciliated
dorsal groove to the mouth where it is swallowed whole. The
posterior half of the worm is segmented and tapers towards the rear,
bearing bristly feet on each segment.
Habitat:In New Zealand. Since about 1995, large areas of shallow sea have been invaded by the worm,
believed to be Chaetopterus variopedatus. By covering the sandy bottom with a dense mat of tubes,
the parchment worm makes life very difficult for the native bottom-dwelling animals. Other marine
worms, clams and starfish have been squeezed out. Bottom-feeding fish and crustaceans probably prey
on C. variopedatus
Reproduction:A female C. variopedatus can produce and liberate a batch of 150,000 to 1 million eggs
into the sea. After fertilisation, the developing larvae become part of the plankton drifting and feeding
for some weeks until they settle. If it becomes injured, this worm has the ability to regenerate its entire
body from a single segment Another anti-predator strategy involves emitting a luminescent cloud of
mucus from its tube.
References.
Retrieved from "http://en.wikipedia.org/w/index.php?title=Chaetopterus&oldid=418262430"
http://www.annelida.net/nz/Polychaeta/Family/Chaetopteridae/chaetopterus-Chaetopterus-A-Pic.htm