Question

Explain adaptive radiations in Polychaeta

Answer 1

Class Polychaeta shows the greatest diversity in Phylum Annelida.  Majority of the 5000 species of polychaetes are marine and exhibit a variety of habits and habitats for which they show anatomical and physiological adaptations.
PLANKTONIC POLYCHAETES
Planktonic polychaetes swim near the surface of the sea where the danger of predators and solar radiation is excessive. 

CRAWLING POLYCHAETES
Crawling polychaetes belong to order Errantia which includes marine, freely moving animals that crawl on sea bottom. 

BURROWING POLYCHAETES
Many polychaetes, such as Nereis crawl on the seabed in night in search of food and   burrow in the soil in day time.  

TUBICOLOUS POLYCHAETES
Tubicolous polychaetes live permanently inside the tubes made of mud, shell or sand grains, parchment or calcium carbonate. 

COMMENSAL POLYCHAETE
  Myzostoma is a commensal that lives in the tubes of other polychaetes or with sea cucumbers and sea stars. 

PARASITIC POLYCHAETES
 Histriobdella lives as ectoparasite in the gill chamber of crustaceans and sucks blood. 

Answer 2

Adaptive radiation is the process where plants or animals evolutionarily diverge from an ancestral species to a variety new forms due to the change in the enviroment.

The class Polychaeta shows greatest diversity in Phylum Annelida. Majority of Polychaeta species are marine.

• Planktonic Polychaeta swim near the surface of the sea where the danger of predators and solar radiation is excessive.
• Crawling polychaeta which crawl on sea bottom.
• Burrowing Polychaeta crawl during night time in search of food and burrow in the soil in the day time.