Glossary

72 terms beginning with R · showing 41–72

1. rhombus

   Oblique-angled, equilateral parallelogram. Often called a diamond.

   Used in 1 profile

2. rib

   Any of a series of slender curved bones articulated to the spine in pairs, serving to protect the thoracic cavity.

   Used in 50 profiles

3. rictal barbel

   Barbel located between the upper and lower jaws, i.e., at or close to the corner of the mouth.

   Used in 2 profiles

4. rictus

   The gape or cleft of the mouth.

   Used in 1 profile

5. ridge

   In morphology, an elongate, raised strip, margin or border on a bone, tooth, tissue membrane, etc.

   Used in 60 profiles

6. riffle

   Short, normally shallow stretch of fast-flowing, turbulent water in a stream; a small rapid; a rocky shoal or sandbar causing such a rapid.

   Used in 105 profiles

7. rift

   Fissure in rock; a shallow or rocky place in a stream resulting in a riffle or rapid.

8. rift

   Narrow fissure or zone of faulting formed via tensional stress in the earth's crust. When such forces are strong or prolonged enough to split the crust apart a central section will typically drop down or subside, sometimes forming a rift valley with steep walls as the gap widens. Water may become impounded in the valley, forming a rift lake.

   Used in 5 profiles

9. rift lake

   Type of lake that forms in a rift zone or rift valley and often very deep with steep cliffs around the margins, also known as a rift valley lake, sag pond, or fault-trough lake. The largest freshwater lakes in the world are all of this type. Also used in the aquarium hobby in reference to the Rift Valley lakes of the East African rift.

   Used in 32 profiles

10. Rift Valley lake

    Generic term for any lake formed in a rift valley, but often used in specific reference to a group located in the East African rift, particularly those lying in its western and southern sections, i.e., the African Great Lakes. In the aquarium hobby the meaning of the term is typically restricted even further to include just lakes Malawi, Tanganyika, and Victoria, the latter of which is not in fact a rift lake and is located in a shallow depression between the eastern and western branches of the main rift. These three lakes are famous for the high number of endemic fish species inhabiting them, especially members of the family Cichlidae.

11. rill

    Small stream.

12. riparian

    Of, inhabiting, or located on the bank of a river or other watercourse, e.g., riparian vegetation.

    Used in 199 profiles

13. river

    Vaguely-defined, generic term for a variably-sized, natural, usually freshwater, watercourse, that empties into an ocean, sea, lake, or another river.

    Used in 1,266 profiles

14. river basin

    Total geographic area drained by a river plus all its tributaries.

    Used in 338 profiles

15. river tank manifold

    Home-made device used to achieve uni-directional flow in an aquarium when inhabitants naturally occur in high-velocity rivers and streams. Typically, one or more powerheads are located at one end of the aquarium with intakes at the opposite end, these being connected via pipework located under the substrate. Though certainly beneficial, this should not be considered an essential requirement in hill stream-type set-ups, however.

16. riverine

    Of, relating to, or situated on a river or riverbank.

    Used in 85 profiles

17. rivulated

    Having irregular streaks.

18. rivulet

    Small stream or brook.

    Used in 4 profiles

19. RNA

    Abbreviation for ribonucleic acid, a single-stranded, self-replicating genetic material comprised of a chain of nucleotides. Present in nearly all living organisms, and replaces and performs the role of DNA in some viruses. Particularly important in protein synthesis and sometimes in transmission of genetic information.

20. robust

    Strong; vigorous; sturdy. Often used to describe the general body form of a fish.

    Used in 246 profiles

21. roe

    Usually refers to a mass of fish eggs or egg-laden fish ovary but sometimes separated into 'hard' and 'soft' roe in reference to the female and male gonads, respectively.

22. rosette

    Roselike marking or collection of markings.

    Used in 1 profile

23. rostral

    In fishes, of, like, or associated with the snout.

    Used in 95 profiles

24. rostral barbel

    Anterior maxillary barbel.

    Used in 105 profiles

25. rostral fold

    A groove between lip and snout.

    Used in 11 profiles

26. rostral spine

    Median dorsal structure located on the snout in certain fishes.

27. rostrum

    In fishes, the snout.

    Used in 23 profiles

28. rotenone

    Chemical extracted from the roots of certain plants, used as a broad-spectrum insecticide, piscicide, and pesticide.

    Used in 1 profile

29. rudimentary

    In biology, incompletely developed; embryonic; vestigial.

    Used in 37 profiles

30. ruggose

    Wrinkled, creased; having a rough surface.

31. rugose

    Wrinkled; corrugated.

    Used in 1 profile

32. runoff

    Rainwater entering a water body as surface water rather than entering the water table or evaporating into the atmosphere.

    Used in 9 profiles