What is the key characteristics of ecdysozoa?
The most distinguishing and prominent feature of Ecdysozoans is their cuticle: a tough, but flexible exoskeleton that protects these animals from water loss, predators, and other aspects of the external environment. All members of this superphylum periodically molt or shed their cuticle as they grow.
Where are most Polychaetes 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 unique about velvet worms?
They have velvety, water-proof skin. Their entire bodies are covered with papillae, tiny protrusions with bristles sensitive to touch and smell. The papillae are made up of overlapping scales, which gives the velvet worm its velvety appearance. It also makes their skin water-repellant.
What are the functions of Parapodium other than for movement?
Gastropod parapodia The fleshy protrusions on the sides of some marine gastropods are also called parapodia. They are particularly well-developed in sea butterflies. Some sea hares use their parapodia to swim. Parapodia can even be used for respiration (similar to gills) or for locomotion.
Are starfish Ecdysozoans?
SUBPHYLUM Asterozoa (free-moving echinoderms with flattened, star-shaped bodies): CLASS Asteroidea (sea stars, also called starfish) These familiar sea creatures are predators that move about with five radial arms. The arms touch one another at their base of attachment to the central disk.
What is an Ecdysozoan and what are some of the unique characteristics of this group of organisms?
Ecdysozoans are a morphologically heterogeneous group of animals which have a cuticle and grow by molting and include the arthropods and nematodes.
What characteristics do polychaetes have?
Class Polychaeta
- Metamerically segmented.
- Bilateral symmetry.
- Chitinous setae called parapodia.
- Schizocoelic.
- Closed circulatory system.
- Complete digestive system.
- Respiration through skin, gills or parapodia.
- Nephridia for excretion.
What is the evolutionary significance of Onychophora?
Biologists are particularly interested in onychophorans because they can help us understand the evolution of one of the most successful groups of animals ever to live on Earth: the arthropods, a clade of segmented animals with jointed legs, that includes insects, spiders, and crustaceans.
What are characteristic features of Onychophora?
Characteristics of the Onychophora: Bilaterally symmetrical and vermiform. Body has more than two cell layers, tissues and organs. Body cavity a true coelom. Most possesses a through straight gut with an anus.
What is the Clitellum and what does it do?
animal reproduction Sexually mature oligochaetes have a clitellum, which is a modification of a section of the body wall consisting of a glandular, saddlelike thickening near the gonopores. During copulation, the clitellum secretes a mucus that keeps the worms paired while sperm are being exchanged.
How are the structures of the Parapodium used in locomotion?
Their locomotion is ensured by five pairs of parapodia located laterally below their trunk. Three pairs of muscles are involved in parapodial motions: parapodium flexor and parapodium extensor, aciculum protractor and aciculum retractor, and hook protractor with conjunctor.