Phylum rotifera asquelminto (microscope image)

What are

Common name for a heterogeneous group of worm-shaped animals with a fluid-filled cavity sometimes used as a skeleton. This cavity is called pseudoceloma because it has no epithelial lining.

Nowadays, it is considered that the skelminths have a series of characteristics that make it necessary to consider each animal in this group belonging to an independent phylum. However, many authors accept the idea of ​​including them in a superfil called Asquelmintos.

Main characteristics of the skeletons

- Long and cylindrical body

- Presence of symmetry on both sides.

- They have no cephalization.

- They have three types of tissues (triblastia): ectoderm, Mesoderm and endoderm.

- The digestive system is complete, consisting of mouth, intestine, rectum and anus.

- They have no cardiovascular or respiratory system.

Best known skeletal filaments:

- Acanthocephala - parasitic worms with a prickly head. There are just over 1000 cataloged species.

- Chaetognatha - small skeletons living in the sea.

- Gastrotricha - about 400 cataloged species, all microscopic.

- Nematoda - also known as roundworms.

- Nematomorpha - also known as endless worms.

- Rotifera - Rotifers are microscopic and live in freshwater.

Biological Curiosities:

- The wormworms can live in both water and soil, or as plant and animal parasites.

- Many species of wormwood can parasitize humans, causing disease.

- Ascaris lumbricoides is a parasitic asquelminto (phylum nematoda) that causes a human disease known as ascariasis.

Chaetognatha, example of marine life asquelminto.