Earthworm: Example of Annelid
What they are - biological definition
Annelids are invertebrate animals with a vermiform aspect that have their bodies segmented into rings.
The phylum Anellida It is large and diverse, with about 16,500 species (known so far).
Annelids, according to the species, live in terrestrial and marine environments. Some species are freshwater, ie, inhabit freshwater environments.
Summary of the main characteristics of annelids:
- They have cylindrical body, elongated and composed of rings.
- The rings do not only represent the outer division of the annelids. In these worms, the internal organs are located in certain rings of the animals' bodies.
- They present bilateral symmetry.
- Have complete digestive system (have mouth and anus).
- They have a closed circulatory system with blood present.
- Most terrestrial species have skin respiration. Those who inhabit aquatic environments are endowed with gills (filaments that act on breathing).
- Presence of musculature in the body wall, responsible for the movement of the animal.
In some annelid species reproduction is sexual (exchange of genetic material, female and male gametes), while in others it is asexual (no presence of male and female gametes).
Examples of Annelids:
- Vermicular Serpula
- Polychaetes (seaworms)
- There are annelids of various sizes, ranging from 1 millimeter to 3 meters in length.
- The word "annelid" comes from Latin, where annellus means ring.
- The worm, one of the best known annelids, is a hermaphrodite animal (has male and female organs in the body).
Leeches: Another example of an annelid animal.