In what ways are molluscs and annelids alike?
Both molluscs and annelids probably evolved from free-living flatworms. Both flatworms and molluscs are triploblastic, bilaterally symmetric, and cephalized. But molluscs have developed a true coelom, an internal body cavity enclosed by mesodermal membranes.
What characteristics are common to mollusks?
Main characteristics of Mollusca :
- Unsegmented soft body with bilateral symmetry.
- Presence of an internal or external shell.
- A toothed tongue (made mostly of chitin) called the radula.
- A mantle which is a fold in the body wall that lines the shell.
- Muscular foot (and/or tentacles in some).
What is the primary difference between animals in the phylum Annelida and Mollusca?
A chitinous scraper called the radula is present in most mollusks. Mollusks are mostly dioecious and are divided into seven classes. The phylum Annelida includes worm-like, segmented animals. Segmentation is both external and internal, which is called metamerism.
What are 5 characteristics of annelids?
Characteristics of Annelida
- The Annelids are coelomate and triploblastic.
- They exhibit organ system level organization.
- Their body is segmented.
- They respire through their body surface.
- Nephridia are the excretory organs.
- They have a well-developed circulatory and digestive system.
What three anatomical features are common to mollusks?
The three most universal features defining modern molluscs are a mantle with a significant cavity used for breathing and excretion, the presence of a radula (except for bivalves), and the structure of the nervous system.
What characteristic defines the clade containing annelids mollusks and flatworms?
Spiral cleavage is characteristic of annelids, mollusks, nemerteans, and related phyla; the clade of animals with this cleavage pattern is therefore known as the Spiralia.
What is the common characteristic of mollusks and crustaceans *?
Crustaceans are aquatic animals that have jointed legs, a hard shell and no backbone, such as crab, crayfish, lobster, prawns and shrimp. Most molluscs have a hinged two-part shell and include clams, mussels, oysters and scallops, as well as various types of octopus, snail and squid.
What is the difference between mollusks and annelids?
Most mollusks have shells. Annelids are worms such as the familiar earthworm. They have segmented bodies. Annelids look like roundworms on the outside, but on the inside they are more like mollusks.
What are the anatomical differences between Nemertines and mollusks?
Mollusks have a shell, even if it is a reduced shell. Nemertines do not have a shell. Nemertines have a proboscis; mollusks do not. Nemertines have a closed circulatory system, whereas Mollusks have an open circulatory system.
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.
Which is a characteristic of all annelids?
annelid, phylum name Annelida, also called segmented worm, any member of a phylum of invertebrate animals that are characterized by the possession of a body cavity (or coelom), movable bristles (or setae), and a body divided into segments by transverse rings, or annulations, from which they take their name.
What are the common names of annelids?
Characteristics of Annelids. The name annelid comes from the Latin word “anellus,” which means little ring.
What are annelids in the taxonomic class?
Annelids belong to the phylum Annelida and they are the diverse group of organisms. This group contains species like earthworms, leeches, and marine worms. Further the annelids can be classified in to three classes. They are: The class Oligochaeta includes freshwater and terrestrial worms, like Lumbricus (earthworms).
What are the most numerous group of annelids?
Polychaeta (Poly = many, Chaeta = bristle) are the most diverse and most speciose group of the Annelida, containing over 5,500 species. Bearded fireworm (Hermodice carunculata) from class polychaeta They are predominantly marine animals and are divided ecologically into the Errantia and the Sedentaria, depending on whether or not they live sedentary lives in holes or live more active lives.
What are all the mollusks?
Mollusks (British spelling: molluscs) are a large and diverse phyla of invertebrate animals, featuring over 110,000 species. Their phylum name, Mollusca , means “thin-shelled,” though many species lack shells entirely. Mollusks include clams, oysters, scallops, mussels, snails, squid, octopuses, slugs, nudibranchs,…