Cloaca

Definition

A cloaca is a common cavity into which the intestinal, urinary, and reproductive tracts open in birds, reptiles, amphibians, and some fish. It functions as an exit for waste products and reproductive cells.

5 Must Know Facts For Your Next Test

1. In birds, the cloaca is the site of copulation where sperm is transferred from the male to the female.
2. The cloaca has three main regions: the coprodeum (receives feces), urodeum (receives urine and reproductive cells), and proctodeum (expels contents).
3. The cloacal kiss refers to the brief contact between male and female cloacas during bird mating.
4. Some vertebrates have a cloacal gland that produces secretions aiding in reproduction or defense.
5. Amphibians utilize the cloaca for both excretion and reproduction, often laying eggs through this opening.

Review Questions

• What are the three main functions of the cloaca in birds?
• Describe what happens during a 'cloacal kiss' in bird reproduction.
• Which vertebrates possess a cloaca?

Related terms

Coprodeum: The section of the cloaca that receives feces from the intestine before excretion

Urodeum: The part of the cloaca where urine and reproductive cells enter before being expelled

Proctodeum: The terminal section of the cloaca through which waste products are expelled