Glossary

63 terms beginning with N · showing 1–40

1. naked

   In ichthyology, scaleless or smooth skin.

   Used in 72 profiles

2. name-bearing type

   In zoological nomenclature, the biological type (normally either a genus, species, or specimen) that determines how a name is applied.

3. nano aquarium

   Small aquarium of arguable definition. Freshwater nano-aquaria are generally accepted to hold between 5-10 US gallons (4.16-8.32 UK gallons; 18.93-37.85 litres) whereas in the marine hobby any aquarium with a volume of 30 US gallons (24.98 UK gallons; 113.56 litres) is generally considered to be a nano-system. These definitions vary, however. Also known as a nano tank.

   Used in 5 profiles

4. nano tank

   See nano aquarium.

5. nape

   In fishes, the part of the dorsal surface between the posterior edge of the skull and dorsal fin insertion.

   Used in 37 profiles

6. nare

   External opening in the nasal cavity; a nostril.

   Used in 4 profiles

7. narial

   Of, relating to, or located close to the nares.

   Used in 12 profiles

8. nasal canal

   Section of the cephalic lateral line canal anterior to the eyes.

9. nasal flap

   Fleshy flap covering or partly covering the nostrils.

10. nasal lamella

    Flap of tissue inside the nostril.

    Used in 14 profiles

11. natal

    Of or relating to the place or time of an orgamism's birth.

12. natant

    Floating on or swimmin in water.

13. native

    Originating in a specific place or area; living or growing naturally in a particular region; indigenous.

    Used in 426 profiles

14. native species

    Species occurring in a given region or ecosystem only as a result of natural processes, with no human intervention.

    Used in 12 profiles

15. natural selection

    Term introduced by Charles Darwin referring to the nonrandom mechanism of evolution by which certain biological traits become either more or less common in a population due to differential, environmentally-influenced reproduction. Better-adapted individuals tend to produce more offspring, thus the population evolves, and this process can result in populations that gradually become specialised to inhabit particular ecological niches and can eventually result in the emergence of new species.

16. naturalised

    Used in reference to an exotic species that has become successfully established in nature outside of its native range.

    Used in 1 profile

17. nauplii

    Plural of nauplius.

    Used in 748 profiles

18. nauplius

    First larval stage in certain crustaceans, comprising an unsegmented body with three pairs of appendages. Important constituent of plankton and the diet of some fishes.

19. necrophagy

    Feeding on carrion.

20. necrosis

    Death of cells or tissue due to disease, injury, or interruption in blood supply.

    Used in 12 profiles

21. neo-

    Prefix meaning 'new'.

    Used in 1 profile

22. neoteny

    Form of paedomorphism characterised by retention of juvenile features in an adult individual via slowed or delayed maturation.

23. neotropical

    Of or relating to a zoogeographical region consisting of South America plus the portion of North America lying south of the tropic of Cancer.

    Used in 65 profiles

24. neotype

    A single specimen designated as the name-bearing type of a species subsequent to its description, most often when the holotype, lectotype, and syntype no longer exist.

    Used in 14 profiles

25. nested

    In cladistics, used to refer to a clade located within a larger clade.

    Used in 33 profiles

26. neural arch

    A bony or cartilaginous arch-shaped structure arising from the dorsal side of a vertebra and enclosing the spinal cord.

    Used in 2 profiles

27. neurocranium

    The section of the skull housing and protecting the brain.

    Used in 5 profiles

28. neuromast

    Individual sense organ of the lateral line system, comprising nerve fibres connected to a cluster of sensory cells.

29. neuromastic pitting

    Severe physical condition of unconfirmed origin occurring in certain fishes which appears related to poor water quality and/or nutrition. The primary symptom is necrosis of the tissue surrounding neuromasts on both the head and body and if left unchecked the disorder can result in death. Similar to, but not analagous with, head and lateral line erosion, and does not appear to occur in nature.

    Used in 1 profile

30. neurotoxin

    A toxin affecting the nervous system.

    Used in 12 profiles

31. neutral

    Neither acidic nor alkaline.

    Used in 179 profiles

32. neutral water

    Pure, ion-free water with a pH of or very close to 7.0.

    Used in 20 profiles

33. new combination

    In zoological nomenclature, the first combination of a generic and previously-published specific name.

34. niche

    The position or role occupied by an organism within an ecological community.

    Used in 39 profiles

35. niche overlap

    An overlap in resource requirements by two or more species.

36. nitrate filter

    See nitrate reactor.

37. nitrate reactor

    Piece of aquarium equipment that can be thought of as an anaerobic filter. Provides a means by which large enough populations of anaerobic bacteria can be maintained so that nitrates are actively removed from the water in the form of nitrogen gas, a process normally facilitated by regular partial water changes. Also known as a nitrogen filter.

38. nitrates

    Any salt or ester of nitric acid, and the end product of the portion of the nitrogen cycle taking place in most closed aquarium systems (the conversion of nitrates to nitrogen gas in natural systems is carried out by anaerobic microorganisms not normally present in sufficient numbers in aquaria, though this process can be induced by installation of a nitrate reactor). While nitrates are less toxic than ammonia or nitrites, they are still potentially harmful to fishes and other aquatic organisms if allowed to accumulate unchecked, and must therefore be diluted via regular water changes. Aquatic plants also help since they are able to metabolise nitrates to an extent.

    Used in 20 profiles

39. nitrify

    To convert ammonia or other nitrogen compounds into nitrites or nitrates.

40. nitrites

    A salt or ester of nitrous acid. Produced in aquaria via metabolisation of ammonia by nitrifying bacteria of the genus Nitrosomonas, and toxic to fishes if present in sufficient concentrations, but in a mature system is further converted into less-harmful nitrates by other bacteria of the genus Nitrospira.

    Used in 1 profile