define the process of nutrition in polychaetes define the process of nutrition in polychaetes
Answers
Polychaetes (bristleworms) are marine annelids with parapodia bearing numerous setae in distinct fascicles. They are dioecious and multi-segmented. They have simple exit ducts from the gonads. Most of them live in soft or rocky environment on sea floor from intertidal to depth. They may be, but rarely, found in freshwater and terrestrial (humid), or parasitic.
The sex of most polychaetes are separate. The gametes produced in a few specialized segments are shed into the coelom and leave the body through the nephridia. After the external fertilization, a ciliated free-swimming trochophore larval is developed.
Other common features of polychaetes include: bisymmetry, metamerism, segmentation, schizocel, closed vascular system, chain nervous system, spiral and determinant cleavage.
Answer:
●Polychaetes as a class are robust and widespread, with species that live in the coldest ocean temperatures of the abyssal plain, to forms which tolerate the extremely high temperatures near hydrothermal vents.
●Polychaetes occur throughout the Earth's oceans at all depths, from forms that live as plankton near the surface, to a 2- to 3-cm specimen (still unclassified) observed by the robot ocean probe Nereus at the bottom of the Challenger Deep, the deepest known spot in the Earth's oceans.