Question

what is the difference between nematods, annelids and arthropods

Answer 1

Nematodes are cylindrical androundworms with un-segmented bodies. Annelids are segmented worms. They possess a true coelom, unlike nematodes which have a pseudocoelom. This is thedifference between Nematodesand Annelids.

Answer 2

Nematods:Nematodes are a type of worms which are cylindrical and not segmented. They are also known as roundworms. They are members of the phylum nematoda of kingdom animalia. There are about one million nematode species according to some estimations. The majority of the nematodes (16,000 species) are parasitic, and this is the reason for the notoriety of roundworms. The largest member of the phylum is about five cm long, but their average length is about 2.5 mm. The smallest species cannot be observed unless observed through a microscope.
Annelida:Annelids are a large phylum consisting of segmented worms, ragworms, earthworms, and nuisance leeches. There are over 17,000 extant species of annelids presently. Usually, they live in freshwater or saltwater as well as around moist terrestrial environments. The body of an annelid is elongated, but segmented externally through ring-like constrictions. These constrictions are called annuli, and they are internally segmented or partitioned via septa at the same places as the annuli. Their segmentation could be regarded as the first sign of differentiation of body parts into different functions. Annelids secrete their cuticle from their skin cells, and the cuticle comprises collagen, but it is not as hard as collagen seen in many other invertebrates.
Artropodas:Arthropods are joint-legged animals and you must have come across a few of these animals. Some prominent ones include insects, spiders, ants, bees, crabs, shrimps, millipedes, centipedes etc. Scientifically speaking, they all come under the Animal Kingdom under phylum Arthropoda.

The success of the arthropods can mainly be attributed to the presence of exoskeleton, which makes them versatile, is protective in nature and also allows flexibility and mobility. You can see arthropods living on land and in water. They are also a source of food for many animals and human beings too!