ECHINODERMS 7 1 



Echinoderms by their development, I propose to mention 

 here a very remarkable group of animals of which the 

 type is Balanoglossus. The animal is a pink or orange 

 worm-like creature varying according to species from a few 

 inches to several yards in length. It is a sand burrower, 

 making a long U-shaped shaft in the sea-bed, one end 

 sometimes ramified into several divergent branches, giving 

 free access to the water. The animal lays eggs which 

 hatch into larvas bearing a strange resemblance to the 

 larvae of Sea Urchins or Starfish, but the adult into which 

 they finally transform has a number of points in common 

 with the vertebrates. It is in fact generally relegated 

 to the phylum Chordata. It possesses for instance a 

 tubular structure — a problematic notochord— and numerous 

 gill-slits, and has no radial symmetry as have the 

 Echinoderms. 



The members of the family abound in tropic seas and 

 one species is common in the Channel Islands. The latter 

 is remarkable for a powerful odour of iodoform, which 

 pervades the creature's burrow and an area of some yards' 

 radius all around it. So tenacious is this odour that 

 it clings to the hands for days despite repeated washing. 



Somewhere between the Echinoderms and the Mollusca, 

 scientists have agreed to place that world-wide group of 

 animals known as Brachyopods. Several forms from 

 deep as well as shallow water are known off our shores. 

 Superficially the Brachyopod resembles a clam or oyster. 

 Its two shells, however, are not, as in bivalve molluscs, 

 placed one on either side of the creature, but are arranged 

 so that one shell is on the back and the other underneath. 



