When were polychaetes discovered?
Polychaetes and their relatives have been around for a very long time. Paleontologists discovered the fossil species Canadia and Burgessochaeta in the Burgess Shale, a famous fossil formation that preserved many soft-bodied organisms dating back some 505 million years ago, during the Cambrian period.
Where are polychaetes 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 is the family of polychaete?
The closest relatives of polychaetes are the earthworms and leeches, which comprise the class Clitellata, all of which are members of the phylum Annelida.
What is unusual about the jaws of some polychaetes?
In general, however, they possess a pair of jaws and a pharynx that can be rapidly everted, allowing the worms to grab food and pull it into their mouths. In some species, the pharynx is modified into a lengthy proboscis.
What type of body organization is found in Polychaetes?
The body in many species, especially in the sedentary polychaetes, is separated into two or three regions. The cells constituting the epidermis (outermost cell layer) are usually simple columnar epithelial cells covered by a cuticle; parts of the body may be ciliated, especially in smaller forms.
What is the most distinctive feature of Polychaetes?
Polychaetes differ from other annelids in having a well differentiated head with specialized sense organs and no clitellum. They have many setae, usually arranged in bundles on the parapodia. The head bears eyes, antennae, and sensory palps.
Does polychaete have clitellum?
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.
Why are polychaetes good environmental indicators?
Among benthic groups, polychaetes are, in fact, one of the best indicators of environmental disturbance, since this taxon contains both sensitive and tolerant species in a gradient from pristine to heavily disturbed habitats (Pocklington and Wells, 1992).
How do earthworms differ from Polychaetes and leeches?
leeches. Leeches are segmented, and thus annelids, and like earthworms they lack the parapodia found in polychaetes and possess a clitellum for reproduction. They differ from earthworms in that they are flatter and actually lack a complete coelomic cavity; which most annelids do have.
What does a fireworm look like?
At first glance, this fire worm looks like a centipede with its elongated and flattened appearance, multiple segments, white silks, and parapodia and gills located on the side of its body. Its colors are varied and range from greenish, to yellowish, to reddish, grayish through white with a pearly glow.
https://www.youtube.com/watch?v=W_m-RiSoh-o