Glossary

Glossary: P

Pacific Ocean

body of water between the southern ocean (above 60 degrees south latitude), Australia, Asia, and the western hemisphere. This is the world's largest ocean, covering about 28% of the world's surface.

Palearctic

living in the northern part of the Old World. In otherwords, Europe and Asia and northern Africa.

Pleistocene

The Pleistocene Epoch began approximately 1.8 million years ago and ended about 11,000 years ago.

palate

the roof of the mouth in vertebrates. The palate can either completely or partially separate the nasal and oral cavities and consists of a hard palate (bony or cartilaginous part) and a soft palate (soft tissues).

papilla

1. A small round or conical projection on the skin, at the root of a hair or feather, or at the base of a developing tooth. 2. One of the small, rounded projections of the upper tongue surface of vertebrates that contain taste buds.

paraphyletic

paraphyly

Referring to a group of organisms with a single, common ancestor, but not containing all of the descendants of that common ancestor within the group.

parenchymula larva

the flagellated, solid-bodied larvaa of some sponges (Phylum Porifera).

parental care

all of the help that a parent gives to its offspring, including (in some cases) feeding, sheltering,and protecting them from predators.

See also: parental investment; no parental involvement

parental investment

parental investing, parental care

the commitment of energy and resources in order to enhance the survival or number of offspring

See also: no parental involvement; parental care

parthenogenic

development takes place in an unfertilized egg

parturition

The process of giving birth.

pastoralism

A social organization based on livestock raising as the primary economic activity.

pelagic

An aquatic biome consisting of the open ocean, far from land, does not include sea bottom (benthic zone).

pentaradial symmetry

pet trade

the business of buying and selling animals for people to keep in their homes as pets.

petaloid

an adjective which describes a form that is similar to a flower petal.

pharynx

the body cavity in vertebrates between the mouth and the esophagus and trachea, it serves as a passageway for both food (on the way to the esophagus) and respiratory gases (on the way to the trachea). The corresponding region in invertebrates is also referred to as the pharynx.

phenotype

phenotypic

Referring to the physical make-up of an individual, or the expression of a particular trait, such as skin color, that may vary between individuals of similar genetic make-up.

See also: genotype

pheromones

chemicals released into air or water that are detected by and responded to by other animals of the same species

photic/bioluminescent

generates and uses light to communicate

photoperiod

the period each day of daylight; daylength.

phylogenetic

Referring to the pattern of evolutionary descent.

See also: taxonomy; systematics

phytoplankton

small plants that float or drift in great numbers in fresh or salt water, especially at or near the surface. These serve as food for many larger organisms. (Compare to zooplankton.)

pinnule

see brachia

piscivore

an animal that mainly eats fish

placenta

An internal organ providing nourishment to and removing waste products from the blood of an unborn young. The unborn young's blood is conveyed to the placenta via the umbilical cord.

placoid scales

placoid

These scales are found on sharks and many rays and chimaeras. They consist of a plate-like base just under the skin, with a spine projecting from the back of the plate onto the surface of the skin. Like mammalian teeth, placoid scales have a hard, enamel-like outer layer that surrounds a pulp cavity supplied with blood vessels. Placoid scales do not get larger as the fish grows, but instead increase in number.

planktivore

an animal that mainly eats plankton

plankton

small plant and animal organisms that float or drift in great numbers in fresh or salt water, especially at or near the surface. These serve as food for many fish and other larger organisms. (See also phytoplankton, zooplankton, and planktivore.)

planula larva

free-swimming, ciliated larval type of cnidarians (Phylum Cnidaria, jellyfish, anemones, and corals). These are usually flattened and oval.

plumage

the coat of feathers of a bird

pneumatic

filled with air pockets

poison

any substance which is harmful to the health of a living organism.

poisonous

an animal which has a substance capable of killing, injuring, or impairing other animals through its chemical action (for example, the skin of poison dart frogs).

polar

the regions of the earth that surround the north and south poles, from the north pole to 60 degrees north and from the south pole to 60 degrees south.

polarized light

light waves that are oriented in particular direction. For example, light reflected off of water has waves vibrating horizontally. Some animals, such as bees, can detect which way light is polarized and use that information. People cannot, unless they use special equipment.

pollination

act of carrying pollen to other flowers, helping plants to reproduce.

polyandrous

Referring to a mating system in which a female mates with several males during one breeding season (compare polygynous).

polyestrous

Referring to a female that has two or more estrus cycles in one breeding season.

polygamous

A mating system where an individual has more than one mate per breeding season.

polygynandrous

the kind of polygamy in which a female pairs with several males, each of which also pairs with several different females.

polygynous

having more than one female as a mate at one time

polymorphic

"many forms." A species is polymorphic if its individuals can be divided into two or more easily recognized groups, based on structure, color, or other similar characteristics. The term only applies when the distinct groups can be found in the same area; graded or clinal variation throughout the range of a species (e.g. a north-to-south decrease in size) is not polymorphism. Polymorphic characteristics may be inherited because the differences have a genetic basis, or they may be the result of environmental influences. We do not consider sexual differences (i.e. sexual dimorphism), seasonal changes (e.g. change in fur color), or age-related changes to be polymorphic.

See also: sexual dimorphism

polyp

the sedentary stage of the life cycle of cnidarians jellyfish, anemones, and corals. Made up of a cylindrical body cemented at one end to a substrate, with a mouth surrounded by a ring of tentacles at the other end.

polyphyletic

polyphyly

Referring to a group of organisms that do not share a common ancestor.

population

A group of animals of the same species that occupies a particular area; usually refers to a group that is somewhat separate from other groups of the same species.

posterior

potamodromous

Referring to fish that live entirely within fresh water.

precocial

offspring is able to locomote and feed or care for itself soon after birth/hatching, often to a limited extent. In birds, covered with down and able to move about soon after hatching.

See also: altricial

predator

an animal that kills and eats other organisms for food.

prehensile

Capable of, or adapted for, grasping.

prey

An animal that is eaten by other animals.

proboscis

A long, flexible nose or trunk.

promiscuous

males and females have multiple partners and there are no long-lasting bonds formed among them.

protonephridia

Singular: protonephridium. A primitive osmoregulatory or excretory organ made up of a tubule ending at a flame bulb, or solenocyte.

protostome

the developmental pattern of animal blastula whereby the blastopore ultimately develops into the mouth, cleavage is typically spiral, and the coelom forms from by splitting.. This pattern is typical of many invertebrate groups (the "Protostomia"), including acoelomate, pseudocoelomate, and coelomate animals. These groups include flatworms, rotifers, nematodes, arthropods, molluscs, annelids, and many others.

protrusible

Referring to an organ or appendage that can be quickly extended or thrust out, such as the mouth of many fishes.

provisioning

provision, provisioned, provisions

providing nourishment

proximal

describing a postion close to the body, compare to "distal".