benthos

 

Chesapeake & Coastal Bay Life 

Illustration of Benthos book

The benthos is the community of organisms that live in or on the bottom of the Bay and its tributaries. Examples of some benthic animals that live in Chesapeake Bay sediments include clams, amphipods, polychaetes, and isopods. Benthic macroinvertebrates are used as biological indicators because they are reliable and sensitive indicators of habitat quality in aquatic environments and they are ecologically important components of the Chesapeake Bay’s food web.

Common Name:Polychaetes
Scientific Name:
Fast Fact:
The word polychaete means "many hairs". Polychaetes are often referred to as "bristle worms," and there are more than 5300 known species in the world!
Kingdom:Animalia
Phyllum:Annelida
Class:Polychaeta
Order1:
Family:
Genus:
Photo or Illustration:Illustration of Polychaetes,  Joann Wheeler 1999
Photo Desc:Illustration of Polychaetes, Joann Wheeler 1999
Photo/Illustration Credit:Artwork by: Joann Wheeler 1999
Size:Up to 3.9 inches
Habitat:
Polychaetes are most common in marine environments world wide. They are typically found in or on the sediments throughout the Chesapeake Bay and its tributaries. Some polychaetes live in stabilized burrows or tubes within the sediments while others are free moving and crawl on top of the sediments.
Reproduction:
A majority of polychaetes reproduce sexually or asexually and a few are hermaphroditic. Those polychaetes that reproduce sexually require the males and females of the species to come together to mate. This can be quite tricky for sessile polychaetes. In order to solve this problem, the body’s hind end breaks off and swims to the surface of the water to spawn. The head end remains in the burrow and later regenerates a new tail. Species that have the ability to reproduce asexually do so by simply budding.
Feeding:
There are two main feeding categories polychaetes fall into: "passive" (filter and deposit feeding) or "active" (grazing, scavenging, parasitizing or predation). Some filter and deposit feeding polychaetes have large spirals of feather-like tentacles that they expand out of their tube and into the water to "catch" food. Other filter and deposit feeding polychaetes move water, and prey, through their burrows by moving their parapodia. Other polychaetes have a more active lifestyle and feed by grazing, scavenging, parasitizing or are predatory. Predatory species have piercing jaws in their throats. The muscular throat can turn inside out to project from the mouth, allowing the jaws to capture prey. Species that use this method also have poison glands that deliver a toxic bite to their prey.
Predators:
Polychaetes are eaten by fishes such as hybrid striped bass (Morone saxatilis and Morone chrysops) and winter flounder (Pleuronectes americanus), starfish such as the pink sea star (Pisaster brevispinus), sea urchins, lobsters, skates such as thorny skate (Raja radiata), crabs such as the horseshoe crab (Limulus polyphemus) and shore birds such as the surf scoter (Melanitta perspicillata).
Description:
In general, polychaetes are marine worms with segmented bodies with each segment having a pair of parapodia and setae. They live in or on the sediments in shore line environments and estuaries. Free moving species move by stroking their parapodia in waves toward the head, similar to how caterpillars move. Several species are sessile and live in burrows or tubes.
Other Facts:
Polychaetes in the genus Eunice reproduce by breaking off their hind ends but only for a few days during a particular moon phase. The females of this genus come out at night and have the unique ability to attract males by producing their own light! In Bermuda and the West Indies, a special festival is held to harvest the hind ends of these polychaetes. In fact, festival participants say eating the hind ends is a delicacy!