How do polychaetes breathe?
The smallest species, and those adapted to burrowing, lack gills, breathing only through their body surfaces. Most other species have external gills, often associated with the parapodia. A simple but well-developed circulatory system is usually present.
Where are the gills of polychaetes?
In the Sedentaria the gills are restricted to a small and often constant number of segments, normally situated in the anterior part of the body (e.g. in Terebellidae). Live observations show that gills of polychaetes can be very mobile and may function as pumps comparable to accessory hearts.
What are two ways the polychaetes respire?
Respiration through skin, gills or parapodia.
How do polychaetes differ from other annelids?
Polychaetes are the most diverse group of annelids and most live in the marine environment. They differ from earthworms and leeches in that they have appendages called parapodia and do not possess a clitellum. In size they range from 1 mm (0.04”) to 3 m (10′) but most are around 10 cm (4”).
What animals eat polychaetes?
Many polychaetes are eaten by other polychaetes and other marine invertebrates as well as fish and wading birds. So polychaetes occupy several levels within the food chain.
Do leeches have parasites?
Most leeches (annelid class Hirudinea) are bloodsucking parasites that attach themselves to vertebrate hosts, bite through the skin, and suck out a quantity of blood.
Are polychaetes Acoelomate?
Unsegmented acoelomate bilaterally symmetrical worms. Digestive tract with seperate mouth and anus, and an eversible proboscis dorsal to the gut in a tubular cavity. The proboscis pore is ventrally located at the anterior end.
How do annelids carry out gas exchange?
Gas exchange generally takes place through the skin, but it may occur through gill filaments in some polychaetes or through the rectum of aquatic oligochaetes. Although oxygen may be transported directly in the blood, it is usually carried by a respiratory pigment, either hemoglobin or chlorocruorin.
Do polychaetes have a closed circulatory system?
Earthworms, leeches, and polychaete worms have a closed circulatory system; meaning, the inner space of their bodies are filled with blood vessels that carry blood, nutrients, and oxygen throughout the body. Like our veins and arteries, these vessels move blood from a series of hearts that lie near the head.
What is the difference between polychaetes and oligochaetes?
The main difference between polychaetes and oligochaetes is that the polychaetes have a pair of parapodia per body segment that bear many bristles. But, oligochaetes have few bristles on their outer surface of the body but, no parapodia. Polychaetes and oligochaetes are two subclasses of phylum Annelida.
How do polychaetes help the environment?
But most importantly, he says, polychaetes may play a vital role in climate control by helping to reduce carbon dioxide in the atmosphere. On the ocean floor, polychaetes help convert organic debris into carbon dioxide, which is transported to the surface dissolved in water.
How does the respiratory system work in polychaetes?
Respiratory gases diffuse through the body wall. The parapodia increase the surface area for gases exchange. In many polychaetes, parapodial gills further increase the surface area for gas exchange. Polychaetes have a closed circulatory system. Oxygen is carried by respiratory pigments.
How are oxygen pigments carried in a polychaete?
In many polychaetes, parapodial gills further increase the surface area for gas exchange. Polychaetes have a closed circulatory system. Oxygen is carried by respiratory pigments. The respiratory pigments are dissolved in the plasma. They are present in the blood cells in other animals.
Where does the blood flow in a polychaete?
The branchiae contain blood vessels and may also contract rhythmically to help circulate the blood. Lateral vessels (side-branches) carry blood from the ventral vessel to the epidermis (‘skin’) and muscles (and to the branchiae in those segments that have them). Some small polychaetes have no blood vascular system at all.
What kind of fluid does a polychaete have?
All polychaetes, however, have a fluid-containing coelom, or body cavity, which occurs betwwen the body wall and the gut and other organs. coelomic fluid.