Glossary

182 terms beginning with P · showing 41–80

1. pea gravel

   Gravel-type consisting of small, rounded grains. Commonly-used as a substrate in aquaria.

2. peat

   A compressed accumulation of partially-decomposed, chiefly vegetable matter typically found in certain marshes, bogs, and peat swamp forests throughout the world. It forms via breakdown of various plants and other organic materials in water when full decomposition is prevented due to localised acidic, anaerobic conditions. As a result of this somewhat specific nature the organisms inhabiting peaty environments are often stenotypic and found nowhere else. Peat can be used as a fuel when dried and thus has industrial importance in some countries. Also used in aquaria, especially in order to simulate blackwater habitats, either in pure, artificially-granulated or liquid extract form.

   Used in 268 profiles

3. peat swamp forest

   Type of tropical moist forest lying over a thick bed of acidic peat, over 60% of which occur in Indonesia and Malaysia. Typically contain water with very low pH (<4.0) that is stained brown due to the release of various organic compounds from the decaying peat and thus often referred to as blackwater swamps. Usually contain some permanent water but also flood seasonally. Highly biodiverse when in pristine condition, with many species found nowhere else on earth, though increasingly subjected to intensive drainage, burning and subsequent conversion to agriculture in recent decades.

   Used in 89 profiles

4. pecking order

   Type of social hierarchy in which individuals within a given group or population are ranked by behavioural and/or physical dominance. Sometimes referred to as a dominance hierarchy.

   Used in 106 profiles

5. pectinate

   Shaped like or resembling a comb; possessing projections that resemble the teeth of a comb.

6. pectoral

   Of, relating to or located on the chest, breast, or thorax; used to refer to a single pectoral fin in relation to fishes.

   Used in 263 profiles

7. pectoral girdle

   Bony or cartilaginous structure supporting the forelimbs or anterior fins in vertebrates.

   Used in 26 profiles

8. pectoral-fin

   Anterior, paired fin attached to the pectoral girdle of fishes, usually just behind the opercle and corresponding to the forelimbs of higher vertebrates. Assists in controlling direction of movement and swimming speed. Frequently abbreviated to 'P' or 'P1' in scientific papers.

   Used in 508 profiles

9. pelagic

   Of, relating to, living or occurring in the open sea rather than coastal or inland habitats.

   Used in 180 profiles

10. pelagic egg

    Egg floating freely in the water column. Sometimes buoyant.

11. pelagic phase

    Period of time during the life cycle spent floating freely in the water column, usually as a larval constituent of plankton. Relatively common in marine fishes but also typical of amphidromous and diadromous species.

12. pellet food

    Commercially-produced, dried, food for fishes compressed into a hard, pelleted form. Usually comprises a combination of macro nutrients, trace elements and vitamins and may contain additional colour-enhancing, medicative or vegetable additives. Available in a range of grain sizes and brands.

    Used in 56 profiles

13. pelvic disc

    Disc-shaped modification of the pelvic fins, which are often fused, used to adhere to surfaces via suction. Present in certain fishes, especially members of the family Gobiidae. Also known as sucking disc.

    Used in 31 profiles

14. pelvic fin

    Either of the pair of fins, also known as pelvic fins, attached to the pelvic girdle in fishes that help control the direction of movement. Correspond to the hind legs in higher vertebrates and vary in position depending on taxon. Sometimes absent entirely.

    Used in 431 profiles

15. pelvic girdle

    Bony or cartilaginous structure supporting the pelvic fins. Sometimes fused with the pectoral girdle.

    Used in 9 profiles

16. peppered

    Term sometimes used in reference to fishes with a colour pattern consisting of many small dots or similar markings.

    Used in 6 profiles

17. pereiopod

    Any of the appendages of a decapod that are used for walking and gathering food.

18. perennial

    Persisting without interruption; enduring; not seasonal.

    Used in 8 profiles

19. perforate

    Pierce; make a hole or holes in.

20. perforated

    Pierced with a single or number of holes, characterised by perforation.

    Used in 23 profiles

21. perforation

    A hole or pattern of holes made by, or seeming to be made by, piercing or boring, especially if occurring in a line or series.

    Used in 1 profile

22. perianal

    Located around or close to the anus.

23. periphyton

    Sessile, aquatic organisms that live attached to submerged surfaces in aquatic environments. Often complex in form and may comprise organisms from several groups including algae, cyanobacteria, other microbes, and detritus.

    Used in 8 profiles

24. peritoneum

    Membranous sac lining the abdominal cavity, the pigmentation of which is sometimes used in identification of fish larvae.

25. pH

    Measure of the acidity or basicity of an aqueous solution. Pure water is said to be neutral, with a pH around 7.0, solutions with pH of less than 7.0 acidic and greater than 7.0 basic or alkaline. Measured on a logarithmic scale of 0.0-14.0 whereby a change of a single unit represents a ten-fold increase in acidity or basicity/alkalinity, i.e., a solution with a pH of 4.0 is ten times more acidic than one of 5.0., and 100 times more acidic than one of 6.0. Some fishes require a relatively specific pH in aquaria, while others are more generalised, with the former requirement often-reduced in captive-bred examples.

    Used in 397 profiles

26. pH crash

    Sudden and rapid drop in pH, usually occurring in aquaria or ponds with poor buffering capacity. Can be fatal to fishes.

27. pharyngeal

    Of, relating to, or located on the pharynx.

    Used in 30 profiles

28. pharyngeal teeth

    Opposing patches of teeth located on the upper and lower portions of the branchial arches in many fishes, e.g., cyprinids. Variable in structure and to an extent, function.

    Used in 55 profiles

29. pharynx

    Section of the alimentary canal connecting the mouth and nasal apparatus with the oesophagus.

    Used in 4 profiles

30. phenology

    Study of periodic events in the life cycle of organisms and their relationship with seasonal and interannual climatic changes, e.g., migration.

31. phenotype

    The observable physical and biochemical traits of an organism, such as its behaviour, external morphology, colour pattern, phenology, etc. Influenced by both genetic and environmental factors.

    Used in 7 profiles

32. phenotypic plasticity

    Ability of an organism to change its phenotype in response to environmental change.

    Used in 2 profiles

33. pheromone

    Chemical secreted by an organism affecting the behaviour or physiology of other individuals of the same species which may function as an alarm or sexual stimulant, for example.

    Used in 2 profiles

34. phosphates

    Any salt or ester of phosphoric acid. The presence or addition of excessive phosphates in aquatic ecosystems can have significant ecological effects such as eutrophication, and they are one of the primary contributors to algal growth in aquaria if allowed to accumulate. Conversely, they may be actively added to heavily-planted set-ups in the form of liquid or other supplements in order to encourage plant growth.

35. photoperiod

    The duration of an organism's daily exposure to light; the period of daylight in each 24-hour cycle.

36. photophore

    Light-emitting organ found in some fishes.

    Used in 1 profile

37. photosynthesis

    Chemical process occurring in the cells of plants, algae and certain other organisms by which carbon dioxide is converted into organic compounds, especially sugars, using the energy from sunlight.

38. phylogenetic

    Of or relating to phylogeny.

    Used in 488 profiles

39. phylogenetic species concept

    Species concept based on the evolutionary relationships among organisms, specifically using common ancestry and shared evolutionary history to define species. Under this concept a species is essentially the smallest group of organisms that share a common ancestor and can be distinguished from other such groups via phylogenetic analyses. Each such grouping constitutes a distinct branch on an evolutionary tree. Subspecies tend not to be recognised and it is generally less restrictive than the biological species concept. Often abbreviated to PSC.

    Used in 1 profile

40. phylogenetics

    The study of evolutionary relatedness among species or other groups of organisms. May be based on morphology, molecular data, or both.

    Used in 3 profiles