What type of body cavity do polychaete have?
What type of body cavity do polychaete have?
coelom
Annelid Features: Elongate and bilateral with segmented true body cavity (coelom) Complete circulatory system with capillaries, arteries and veins. Body wall made of circular and lengthwise muscles. Continuous gut running from mouth to anus.
What does polychaete mean in biology?
polychaete. / (ˈpɒlɪˌkiːt) / noun. any marine annelid worm of the class Polychaeta, having a distinct head and paired fleshy appendages (parapodia) that bear bristles (chaetae or setae) and are used in swimming: includes the lugworms, ragworms, and sea mice.
What kind of animal is a polychaete?
Polychaete, any worm of the class Polychaeta (phylum Annelida). About 8,000 living species are known. Polychaetes, which include rag worms, lugworms, bloodworms, sea mice, and others, are marine worms notable for well-defined segmentation of the body.
What are 3 characteristics of annelids?
Characteristics of Phylum Annelida
- They have a long and segmented body.
- Annelids are bilaterally symmetrical.
- They are triploblastic.
- Also, they exhibit organ system grade of organisation, showing organ differentiation.
- The body is covered with a thin cuticle.
- They are coelomate.
What type of body cavity do Mollusca have?
But molluscs have developed a true coelom, an internal body cavity enclosed by mesodermal membranes. The coelom in molluscs, however, is strangely reduced to a small space around the heart, sometimes called a hemocoel.
What are the common names of two types of polychaetes?
Polychaetes are known by many names: lugworms, clam worms, bristleworms, fire worms, palolo worms, sea mice, featherduster worms, etc., but all possess an array of bristles on their many leg-like parapodia — the name polychaete, in fact, means “many bristles”.
What does polychaete look like?
The known species of polychaetes share only a few characteristics. Each has a head, a tail and a segmented body, and typically each body segment has a pair of leg-like parapodia with spiny bristles sticking out. It’s these bristles that give the worms their name: “polychaete” is Greek for “with much hair.”
Where is polychaete found?
ocean
Of the approximately 9000 species of annelids, more than 8000 are polychaetes. These segmented worms are among the most common marine organisms, and can be found living in the depths of the ocean, floating free near the surface, or burrowing in the mud and sand of the beach.
Where are polychaete found?
oceans
Polychaetes are multi-segmented worms living in all environments in the world’s oceans, present from abyssal depths to shallow estuaries and rocky shores, and even free swimming in open water. They are strictly aquatic annelids, but are the most abundant and diverse group of Phylum Annelida.
What are the body segments of a polychaete made of?
Polychaete. The Polychaeta /ˌpɒlɪˈkiːtə/, also known as the bristle worms or polychaetes, are a paraphyletic class of annelid worms, generally marine. Each body segment has a pair of fleshy protrusions called parapodia that bear many bristles, called chaetae, which are made of chitin.
Where does a polychaete get its gametes from?
Most polychaetes have separate sexes, rather than being hermaphroditic. The most primitive species have a pair of gonads in every segment, but, in most species, there has been some degree of specialisation. The gonads shed immature gametes directly into the body cavity, where they complete their development.
Which is the most common polychaete in the world?
Common representatives include the lugworm (Arenicola marina) and the sandworm or clam worm Alitta. 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.
What kind of tubes do sedentary polychaetes use?
Parapodia, if present, are generally simple lobes; frequently the setae project directly from the body wall. Many sedentary polychaetes construct tubes made from a substance secreted from cells that constitute the epidermis, or skin. Tubes may consist of calcium carbonate, parchment, or mucus, to which sediment adheres.