What type of worms are polychaetes?
Polychaetes, which include rag worms, lugworms, bloodworms, sea mice, and others, are marine worms notable for well-defined segmentation of the body. Unique among annelids, most polychaete body segments bear a pair of parapodia (flat, lobelike outgrowths) with setae, or tiny bristles.
What animals are in the class oligochaeta?
Specifically, oligochaetes comprise the terrestrial megadrile earthworms (some of which are semiaquatic or fully aquatic), and freshwater or semiterrestrial microdrile forms, including the tubificids, pot worms and ice worms (Enchytraeidae), blackworms (Lumbriculidae) and several interstitial marine worms.
Is a polychaete a invertebrate?
sedentary polychaete | invertebrate | Britannica.
What organisms are in polychaeta?
Polychaetes include such forms as sand worms, tube worms, and clam worms. Most have well developed, paired, paddle-like appendages (parapodia), well developed sense organs, and numerous setae (usually on the parapodia; “polychaete” means “many hairs”).
What is example of Oligochaeta?
What are the characteristics of class polychaeta?
- Metamerically segmented.
- Bilateral symmetry.
- Chitinous setae called parapodia.
- Closed circulatory system.
- Complete digestive system.
- Respiration through skin, gills or parapodia.
- Nephridia for excretion.
Where are polychaeta found?
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 is the nature of Seta in polychaeta?
Polychaeta (meaning “many setae”) is conveniently though not clearly divisible into the Errantia, or free-moving annelids, and Sedentaria, or tubicolous families. The body may be long, cylindrical, and multisegmented, or short and compact, with a limited number of segments.
Are earthworms Errantia and Sedentaria?
Based on these results, Annelida was split into two major clades, one clade (the Errantia) adapted to an errant mobile life and the other (the Sedentaria) which includes earthworms and leeches, to a more sessile, sedentary one.
What are characteristics of polychaeta?
Most have well developed, paired, paddle-like appendages (parapodia), well developed sense organs, and numerous setae (usually on the parapodia; “polychaete” means “many hairs”). Polychaetes usually have a well-developed head, often complete with well-developed eyes, antennae, and sensory palps.
Are Polychaeta worms marine or terrestrial?
The Polychaeta: Worms, Worms and More Worms. The Polychaeta is the largest and the most diverse of the Annelid groups. Most species are marine, but some have adapted to brackish or even fresh water and a very few are terrestrial.
What are the characteristics of polychaetes?
Sedentary polychaetes normally have their body divided into two, or sometimes three, distinct sections or tagma. They usually have their secretory organs in the anterior, or front, section of their bodies. This allows them to direct their wastes towards the outside of their tube. Many species also have gills on some segments of their bodies.
Are polychaetes free living predators?
About half the known polychaeta are free living predators or scavengers – and the other half live permanently in burrows. This has resulted in the polychaeta being divided into two ecological groups: the active forms that move around searching for food (called the Errantia)
Why do Polychaeta have long nephridial tubes?
In species that live in fresh water – or environments with variable salinity – such as Nereis sp., the nephridial tubes are longer to help them deal with the greater osmotic potential occurring between their inner body fluids and the fluids of the environment they are living in. The Polychaeta exhibit a wide range of lifestyles.