Is a nematode a mollusk?
Nematodes are not so obviously related to annelids and molluscs, either in the structure of the animals themselves or in the form of their embryos.
What is the difference between mollusks and worms?
Mollusks are invertebrates such as the common snail. Most mollusks have shells. Annelids are worms such as the familiar earthworm. They have segmented bodies.
How are mollusks and worms alike?
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 classifies a mollusk?
Molluscs are a clade of organisms that all have soft bodies which typically have a “head” and a “foot” region. Often their bodies are covered by a hard exoskeleton, as in the shells of snails and clams or the plates of chitons.
Which of the following are characteristics of mollusks?
Mollusca Characteristics
- They are mostly found in marine and freshwater.
- They exhibit organ system level of organization.
- Their body has a cavity.
- The body is divided into head, visceral mass, muscular foot and mantle.
- The head comprises of tentacles and compound eyes.
- The body is covered by a calcareous shell.
What is the difference between worms and nematodes?
Most worms have two bands of muscles: longitudinal muscles that run the length of the body and circular muscles that form circular bands around the body. Unlike other worms that have two bands of muscles, nematodes only have longitudinal muscles.
What is the difference between a nematode and an earthworm?
The main difference between Nematoda and Annelida is that Nematoda has a cylindrical body with tapered ends whereas Annelida has a cylindrical body, which is segmented. Therefore, Nematoda is called roundworms while Annelida is called segmented worms.
Are mollusks related to worms?
Molluscs include such familiar creatures as clams, oysters, snails, and octopi. They share a distant common ancestor with the annelid worms, an evolutionary heritage suggested by their larval form, called a trochophore larva, found in all molluscs and in certain marine annelids called polychaete worms.
Are nematodes vertebrates or invertebrates?
invertebrates
Nematodes, as members of the phylum Nemata (or Nematoda), are one of the most abundant groups of invertebrates on earth and rival the Arthropoda in biodiversity and species abundance.
What are the main characteristics of nematodes?
Following are the important characteristics of Nematoda:
- Their body is bilaterally symmetrical and triploblastic.
- They are cylindrical in shape.
- They exhibit tissue level organization.
- Their body has a cavity or pseudocoelom.
- The alimentary canal is distinct, with the mouth and the anus.
- They are sexually dimorphic.
What is the distinguishing characteristics of nematodes?
Nematodes are bilaterally symmetrical, elongate, and usually tapered at both ends. Some species possess a pseudocoel, a fluid-filled body cavity between the digestive tract and the body wall. Like arthropods and members of six other phyla, nematodes secrete an external cuticle that is periodically molted.
What are 3 characteristics of mollusks?
What are the 4 distinguishing characteristics of molluscs?
Molluscs. The phylum Mollusca is defined by several special characteristics. These defining characteristics include a mantle with a mantle cavity, a shell (except where lost), visceral mass, foot, and radula. The odontophore is in the mouth of most mollusks and it supports the radula (a ribbon of teeth).
What common features do all mollusks have?
WHAT FEATURES DO MOLLUSKS HAVE IN COMMON? As well as a shell, most mollusks have a muscular foot for creeping or burrowing. Some also have a head with sense organs. The soft body includes lungs or gills for breathing, and digestive and reproductive parts, all enclosed by a skinlike organ called the mantle.
What is the difference between nematodes and platyhelminthes?
The phylum Platyhelminthes contains flatworms, whereas nematodes are roundworms. Platyhelminthes are acoelomate, whereas nematodes have pseudocoelom. Platyhelminthes are hermaphrodites or monoecious, whereas nematodes are dioecious, i.e. sexes are separate.