Glossary

72 terms beginning with O · showing 41–72

1. osmotic shock

   Rupture of cells in a solution as a result of a sudden reduction in osmotic pressure. Can cause severe issues in fishes when the chemical composition of the water changes rapidly, e.g., during or following a pH crash.

2. osseus

   Composed of, containing, or resembling bone; bony.

3. ossicle

   Small bone, especially any of the three small bones in the inner ear of vertebrates.

   Used in 4 profiles

4. ossification

   The natural process of bone formation.

   Used in 1 profile

5. ossify

   To change into bony or become bony.

6. Ostariophysan

   Fish of the superorder Ostariophysi, members of which are characterised by possession of a Weberian apparatus, i.e., the anterior four or five vertebrae are modified as a protective casing for the bony ossicles which connect the inner ear and swim bladder. The order contains such orders as Cypriniformes, Characiformes, Gymnotiformes, and Siluriformes.

7. Osteichthyes

   Superclass of fishes possessing bony, as opposed to cartilaginous, skeletons. Also known as bony fishes.

   Used in 20 profiles

8. osteocranium

   The bony part of the skull.

9. osteology

   Study of the structure and function of bones.

   Used in 3 profiles

10. ostracod

    Any member of the crustacean class Ostracoda.

    Used in 14 profiles

11. Ostracoda

    Class of crustacean, sometimes referred to as seed shrimp, characterised by possession of a bivalve-like protective carapace. Found in both freshwater and marine environments, and sometimes used as food for small fishes in aquaria.

12. otolith

    Calcareous structures contained within the inner ear of most fishes, functioning to provide a sense of balance in a similar way to the inner ear in humans, as well as aiding in hearing. Also known as ear bones, ear stones or statoliths. Accumulate layers of calcium carbonate and gelatinous matrix as a fish ages, these forming structures comparable to tree rings which can be used to ascertain the age of an individual, even to the precise day.

    Used in 1 profile

13. outcross

    The process of outcrossing or offspring resulting from it.

14. outcrossing

    A cross between relatively unrelated individuals; the introduction of unrelated genetic material into a breeding line. Often used to raise or maintain genetic diversity.

15. outgroup

    In phylogenetics, a group of organisms serving as a reference and comparison to the groups being studied. Opposite of ingroup.

16. ova

    Plural of ovum.

17. overstock

    To add more fishes to an aquarium than it is capable of maintaining in a biological or physical sense.

18. oviparous

    Producing eggs which hatch outside the body, as in most fishes.

19. oviposit

    To deposit an egg during a spawning event,

20. ovipositor

    Tubular structure used to deposit eggs in some fishes. Formed by an extension of the genital opening and usually concealed but sometimes becomes visible prior to spawning. Also referred to as the genital papilla.

    Used in 31 profiles

21. ovoid

    Egg-shaped.

    Used in 2 profiles

22. ovophilous

    Of or relating to ovophily.

    Used in 17 profiles

23. ovophily

    Reproductive strategy whereby the eggs are laid on a solid surface where they are immediately collected and brooded in the mouth of one or both parents. Seen in some Geophagus spp., for example.

24. ovoviviparity

    Reproductive strategy in which fertilisation occurs internally and the eggs develop inside the body of the mother until hatched, at which point live offspring are born. There is no placental connection between mother and embryo unlike in viviparous species.

25. ovoviviparous

    Exhibiting ovoviviparity.

26. ovum

    Unfertilised female reproductive cell or gamete; unfertilised fish egg.

27. oxbow

    See oxbow lake.

28. oxbow lake

    Crescent or U-shaped lake formed when a meander of a river or stream is separated from the main channel. Less commonly used in reference to any U-shaped bend in a river or stream whether separated or not.

    Used in 65 profiles

29. oxidation

    Chemical process whereby an atom or ion loses electrons and undergoes a subsequent increase in valence; the combination of a substance with oxygen; the act or result of being oxidised. Opposite of reduction.

30. oxycercal

    Used in reference to a caudal fin with a tapering shape.

31. oxygenation

    Process of providing, combining, or treating with oxygen.

    Used in 273 profiles

32. oxytetracycline

    Broad spectrum antibiotic used to treat both gram-negative and gram-positive bacterial infections.