Glossary | O

Oblique
having a slanting or sloping direction or position
Oceanography
study of the science of the world's ocean
Ocelli
non-imaging producing, small cup shaped structures at tentacle bases of jellies that function as light sensing organs
Olfactory
pertaining to the sense of smell
Omnivore
animal that feeds on both animal and plant matter
Operculum
hard flap serving as a cover for the the gill slits in fishes or the opening of the shell in some gastropods when the body is retracted into the shell
Opportunistic feeder
animal that feeds on whatever is available
Oral
of or pertaining to the mouth
Oral arms
structures around the mouth of jellies that aid in the capture and ingestion of food; may contain stinging cells and serve in sexual reproduction process
Organic
derived from living organisms
Osmoregulator
physiological mechanism used in an organism to regulate salt and fluid balance of the body to an acceptable level
Oviparous
egg-laying with young hatching outside female's body
Ovoviviparity
(now called aplacental viviparity). Eggs are incubated and hatched within the female's body, but without the formation of a placenta. Young are born live.