Glossary

171 terms beginning with S · showing 41–80

1. setaceous

   Having, resembling or consisting of bristles.

2. sex

   See gender. Also used to refer to the process of distinguishing the gender of an individual; sexing.

   Used in 304 profiles

3. sex ratio

   The ratio of males to females in a given population. Often used to describe the same ratio in a batch of captive-bred fishes.

   Used in 5 profiles

4. sexing

   The process of distinguishing the gender of an individual.

   Used in 30 profiles

5. sexual dichromatism

   Difference in colour pattern between males and females of a single species.

   Used in 4 profiles

6. sexual dimorphism

   Phenotypic difference between males and females of a single species. Used in species profiles here on SF to refer to differences in morphology or colour pattern, but officially also refers to behavioural differences.

   Used in 99 profiles

7. shimmies

   Behavioural symptom that indicates deteriorating water quality or disease in which an individual appears listless with fins normally clamped to the body and displays an abnormal, 'shimmying' swimming action. Particularly typical in poeciliid livebearers.

8. shoal

   A group of fishes, normally of the same species, that remain close to each other for some reason. Differs from a school in that individuals are not necessarily swimming together in the same direction. Also used to refer to a shallow area in a water body.

   Used in 101 profiles

9. sibling

   One of two or more individuals having one or both parents in common; a brother or sister.

   Used in 6 profiles

10. sibling species

    One of two or more very closely-related species that are reproductively isolated from one another but almost indistinguishable in morphologically and/or behaviourally. May occur sympatrically and even interbreed but are incapable of producing fertile hybrid offspring. Sometimes referred to as cryptic species.

    Used in 3 profiles

11. silica sand

    Sand containing a high concentration of silicon dioxide. Noted in aquaria for its purity, delicate appearance and lack of effect on water chemistry. Also known as silver sand.

12. silicate

    Any of a largegroup of chemical compounds containing silicon, oxygen, and at least one metal. Most rocks and minerals are silicates.

13. silver sand

    See silica sand.

14. simple ray

    Unbranched and unsegmented soft fin ray.

    Used in 20 profiles

15. single-access key

    A dichotomous or otherwise sequential identification key. See dichotomous key.

16. sinuate

    Having a wavy margin with strong indentations.

17. sister

    See sister group.

18. sister group

    In cladistics, a monophyletic group more closely related to the group in question than any other, i.e., the closest outgroup. Sister groups normally share an immediate common ancestor.

    Used in 212 profiles

19. skeleton

    In vertebrates, the internal structure composed of bone and/or cartilage that supports the soft tissues and protects the internal organs.

    Used in 15 profiles

20. skin

    In vertebrates, the thin, membranous layer of external tissue forming the protective covering of the body.

    Used in 399 profiles

21. sneaker male

    Subdominant male individual of certain fish species that attempts to sneak into the nest of a spawning pair and fertilise deposited eggs. Typically smaller in size and/or possessing reduced colouration compared with a normal male. Also known as a sneaky male.

22. sneaky male

    See sneaker male.

23. snout

    The projecting mouthparts, jaws, or part of the head anterior to the eyes.

    Used in 285 profiles

24. snout length

    Distance between the tip of the upper jaw and anterior margin of the orbit.

    Used in 30 profiles

25. soft ray

    Segmented fin ray which is flexible and usually branched.

    Used in 17 profiles

26. soft water

    Water containing low concentrations of mineral salts, especially calcium or magnesium.

    Used in 78 profiles

27. Solimões

    Name often given to the Amazon River main channel from its confluence with the Rio Negro upstream to the border of Brazil and Peru. Often used interchangeably with 'Amazon' to describe this stretch.

    Used in 31 profiles

28. sp.

    Abbreviation for species.

29. spawn

    The eggs of fishes and other aquatic organisms; to deposit and fertilise such eggs.

    Used in 673 profiles

30. spawning

    The act of releasing and fertilising eggs in fishes.

    Used in 988 profiles

31. spawning migration

    Migration of fishes to a spawning site or area, occurring in certain fishes. Variable in extent.

    Used in 10 profiles

32. spawning substrate

    Particular substrate type required by a given egg-laying fish species for the purpose of spawning.

    Used in 9 profiles

33. speciation

    Evolutionary formation of new biological species.

    Used in 13 profiles

34. species

    Taxonomic rank into which a genus is divided, but otherwise difficult to delineate precisely with a single definition satisfying all eventualities still lacking to date. There exist a number of concepts of which the most popular in vertebrate taxonomy include the biological species concept and phylogenetic species concept.

    Used in 1,790 profiles

35. species flock

    Diverse group of closely-related, biologically distinct species occurring in an isolated area.

36. species inquirenda

    Latin term meaning a species of doubtful identity requiring further investigation; a questionable species.

    Used in 2 profiles

37. species name

    Scientific name of a species; binomen.

    Used in 25 profiles

38. species nova

    New species, usually given after the species name in a description instead of the author. Abbreviated to sp. nov. or sp. n.

39. species richness

    The number of species present in a given sample, habitat, or otherwise specified geographical region.

40. specific epithet

    In zoological nomencature, the second name in a binomen and in a trinomen. Has no nomenclatural function when used alone, though this is often done in aquarium literature or when referring to a species in passing if the genus being referred to is already clearly known. Also known as specific name.

    Used in 24 profiles