Invertebrate animals commonly called "worms" include annelids (earthworms and marine polychaete or bristle worms), nematodes (roundworms), platyhelminthes (flatworms), marine nemertean worms ("bootlace worms"), marine Chaetognatha (arrow worms), priapulid worms, and insect larvae such as grubs and maggots.
Why are earthworms in a different group than roundworms?
One of the most prominent differences between roundworms and segmented worms is their circulatory systems. Segmented worms have a complete circulatory system, while round worms do not. A segmented worm's circulatory system includes blood, heart, capillary system and hemoglobin.
What are roundworms classified as?
Worms with round, non-segmented bodies are known as nematodes or roundworms (Figure below). They are classified in the phylum Nematoda, which has over 28,000 known species. Some scientists believe there could be over a million species of Nematodes.
Why roundworm and earthworm are not in the same phylum?
The main difference between Ascaris and earthworm is that Ascaris is a parasitic roundworm that causes illness whereas earthworm is a segmented worm beneficial to the soil. Furthermore, Ascaris belongs to the phylum Nematoda while earthworm belongs to the phylum Annelida.
What do earthworms and roundworms have in common?
All of them are invertebrates. They all have long, narrow bodies without legs. All worms also have tissues, organs, and organ systems. Worms have bilateral symmetry.
