Velum

Definition

The velum is a membranous structure found in certain cnidarian medusae, such as hydromedusae. It forms a rim around the inner margin of the bell and aids in locomotion.

5 Must Know Facts For Your Next Test

1. The velum is primarily present in hydrozoan medusae but absent in scyphozoan medusae.
2. It functions by contracting to expel water, propelling the medusa through its environment.
3. The presence of the velum distinguishes hydromedusae from other types of jellyfish.
4. It plays a role in regulating the flow of water into and out of the gastrovascular cavity.
5. The development of a velum can be an indicator of evolutionary adaptations within different cnidarian species.

Review Questions

Related terms

Medusa: The free-swimming, umbrella-shaped stage in the life cycle of some cnidarians, such as jellyfish.

Gastrovascular Cavity: A central digestive compartment with one opening that serves as both mouth and anus in cnidarians.

Cnidocytes: Specialized cells unique to cnidarians that contain stinging structures used for defense and capturing prey.