What do annelids and mollusks have in common?
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 evidence exists to indicate that annelids and mollusks are closely related?
What evidence exists to indicates that mollusks and annelids may be closely related? Because they have specific jobs that they do.
What clade of animals do both annelids and mollusks belong to?
The phyla Mollusca and Annelida belong to a clade called the Lophotrochozoa, which also includes the phylum Nemertea, or ribbon worms (see: Features of the Animal Kingdom: phylogenetic tree of animals).
What do mollusks and worms have in common?
Similarities between mollusks and segmented worms suggest that they could have a common ancestor. These groups were the first animals to have a body cavity with space for body organs to develop and function. Mollusks and segmented worms have a one-way digestive system with a sepa- rate mouth and anus.
What is the connecting link between Annelida and Mollusca?
Connecting link between annelida and mollusca is neopilina.
How do molluscs differ from other animals?
Molluscs have a mantle or mass of soft flesh that covers the soft body and encloses the internal organs. In many species, the mantle produces a hard shell. Not all molluscs produce a shell. Many molluscs have a radula, which, in most species, is a rasp-like scraping organ used in feeding (Fig.
Why are annelids arthropods and mollusks placed in the same clade?
Why are annelids, arthropods, and mollusks placed in the same clade? – They are diploblastic.
What are annelids most closely related to?
Annelids and arthropods have long been considered each other’s closest relatives, as evidenced by similarities in their segmented body plans.
What is connecting link between Annelida and Arthropoda?
Peripatus is a connecting link between Annelida and Arthropoda.
What is the connecting link between Mollusca and echinodermata?
Peripatus is a connecting link between mollusks and echinodermata.
How are molluscs different from other invertebrates?
As nouns the difference between invertebrate and mollusc is that invertebrate is an animal without vertebrae, ie backbone while mollusc is a soft-bodied invertebrate of the phylum mollusca, typically with a hard shell of one or more pieces.
What is the basic anatomy of annelids?
Annelids have a well-developed nervous system with two ventral nerve cords and a nerve ring of fused ganglia present around the pharynx. Figure 15.29 In this schematic showing the basic anatomy of annelids, the digestive system is indicated in green, the nervous system is indicated in yellow, and the circulatory system is indicated in red.
Why are molluscs distinct from other invertebrates?
They are distinct from the Ecdysozoa (nematodes and arthropods) based on evidence from analysis of their DNA, which has changed our views of the relationships among invertebrates. Mollusca is the predominant phylum in marine environments, where it is estimated that 23 percent of all known marine species belong to this phylum.
What is the dorsal epidermis modified to form in mollusks?
The dorsal epidermis in mollusks is modified to form the mantle, which encloses the mantle cavity and visceral organs. This cavity is distinct from the coelomic cavity, which the adult animal retains, surrounding the heart. Respiration is facilitated by gills known as ctenidia.
What phylum are Mollusca and Annelida in?
The phyla Mollusca and Annelida belong to a clade called the Lophotrochozoa, which also includes the phylum Nemertea, or ribbon worms ( [link]). They are distinct from the Ecdysozoa (nematodes and arthropods) based on evidence from analysis of their DNA, which has changed our views of the relationships among invertebrates.