Glossary: S

  1. Relating to the suture between the two parietal bones of the skull in vertebrates. 2. Relating to the sagittal plane, which extends through the midline of a bilateral animal, dividing it into two equal halves.

The ecoclimatic region that borders the Sahara Desert to the south in the 6000 km (3720 mi) long, 500 km (310 mi) wide strip crossing the continent of Africa from the Atlantic Ocean to the Red Sea between the 100 mm (4) and 600 mm (24) isohyets of mean annual rainfall. The word Sahel comes from the Arabic word for edge.


specialized for leaping or bounding locomotion; jumps or hops.

saltwater or marine

mainly lives in oceans, seas, or other bodies of salt water.


an animal that mainly eats blood


A grassland with scattered trees or scattered clumps of trees, a type of community intermediate between grassland and forest. See also Tropical savanna and grassland biome.


An organism that is specialized for climbing.


an animal that mainly eats dead animals

scent marks

communicates by producing scents from special gland(s) and placing them on a surface whether others can smell or taste them

scientific name

The scientific name of an animal consists of two levels of its taxonomic classification, the genus and species. Scientific names are in Latin. They are usually printed in italics, with the genus capitalized. Thus the scientific name of the tiger is Panthera (genus) tigris (species). Sometimes a species is further subdivided into subspecies, and the subspecies name is added to the scientific name. Thus the Siberian tiger's scientific name is Panthera tigris altaica. Once the genus and species have been mentioned, they are usually abbreviated in subsequent occurrences (e.g. the Siberian tiger's scientific name would be written P. t. altaica.)

sclerophyll forest

A general term for hard-leafed forest, such as the eucalypt forest that covers much of Australia.


An accumulation of stones or rocky debris lying on a slope or at the base of a hill or cliff.

scrub forest

scrub forests develop in areas that experience dry seasons.


a larva of a scyphozoan (Phylum Cnidara, Class Scyphozoa, a group of jellyfish), made up of an elongated and constricted polyp which buds off swimming medusae.

seasonal breeding

breeding is confined to a particular season


remains in the same area

seed dispersal

helps spread the seeds of a plant


offspring are all produced in a single group (litter, clutch, etc.), after which the parent usually dies. Semelparous organisms often only live through a single season/year (or other periodic change in conditions) but may live for many seasons. In both cases reproduction occurs as a single investment of energy in offspring, with no future chance for investment in reproduction.

septal filaments

Free edges on the septa in the gastrovascular cavity of anthozoans, which contain nematocysts to help paralyze prey. Synapomorphy of Anthozoa.

septate shell

Shell divided into smaller chambers. Synapomorphy of the Cephalopoda.

sequentially hermaphroditic

condition of hermaphroditic animals (and plants) in which the organs and products of one sex appear before the organs and products of the others, thus preventing self-fertilization.


Relating to a series of ecological communities that succeed one another in the biological development of an area.


non-motile; permanently attached at the base.

Attached to substratum and moving little or not at all. Synapomorphy of the Anthozoa


A stiff hair-like structure, made of chitin, often found on fleshy appendages. Synapomorphy of the Annelida.


reproduction that includes combining the genetic contribution of two individuals, a male and a female

sexual dimorphism

sexes are somehow different in appearance.

sexual ornamentation

one of the sexes (usually males) has special physical structures used in courting the other sex or fighting the same sex. For example: antlers, elongated tails, special spurs.


A range of mountains, especially with a serrated or irregular outline.

simultaneously hermaphroditic

condition of hermaphroditic animals (and plants) in which the reproductive organs of both sexes are present and functional at the same time


Grooves that run down the pharynx to the mouth, which are covered with cilia and pump water into the animal's body. Synapomorphy of Anthozoa.


Living cord which connects all the chambers in septate shells. Synapomorphy of the Cephalopoda.


associates with others of its species; forms social groups.

soil aeration

digs and breaks up soil so air and water can get in


lives alone


The collective term for a group of pigs.


the eggs of certain aquatic organisms

spawning season

the time of year during which certain organisms release their gametes or eggs into the water, resulting in fertilization.


A taxonomic division that generally refers to a group of animals which are similar in structure and descent and are able to breed among themselves.

species flock

Referring to an ecologically distinct group of species descended from a single parent (monophyletic) that have evolved in an isolated geographic area (i.e. lake or island).


A person who explores and/or studies caves.


mature spermatozoa are stored by females following copulation. Male sperm storage also occurs, as sperm are retained in the male epididymes (in mammals) for a period that can, in some cases, extend over several weeks or more, but here we use the term to refer only to sperm storage by females.

See Also: delayed fertilization

a packet enclosing sperm, produced by males of several invertebrate groups and some vertebrates.


the minute calcareous or siliceous skeletal bodies found in sponges (Phylum Porifera), radiolarians (a protist group), soft corals (Phylum Cnidaria), and sea cucumbers (Phylum Echinodermata).


any hardened, spike-like projection used to defend an organism from predation, such as the hardened hairs of porcupines, sharp rays on a fish's fins, or sharp projections of a clam shell.


A grass which grows in large, distinctive clumps or hummocks in the driest areas of central and western Australia.

spiral cleavage

the egg cleavage pattern characterisic of protostomes (Protostomia, see protostome), in which egg cleavage result in a spiralled mass of cells.


a fibrous material made up of the skeletal network of horny sponges.

startle coloration

A coloration pattern used by animals to startle predators. Often the startle coloration is only exposed when the animal is startled, in turning startling the predator. Examples are eye spots or bright colors.


a fluid-filled cellular cyst containing granules (statoliths), used to sense direction of gravity. Statocysts act as sense organs of equilibrium.


Open grassy plains in the temperate zone, characterized by low and sporadic rainfall and a wide annual temperature variation.


Random; exhibiting variability due to random events.

stores or caches food

places a food item in a special place to be eaten later. Also called "hoarding"


a term used to describe animals which burrow or live under the snow.

subradular organ

a chemosensory organ found in chitons (Phylum Mollusca: Class Polyplacophora). It is a modified portion of the foregut that can be extruded to touch the food before eating.


A surface on which something grows or is attached. As in "barnacles grow on hard substrates." The bottoms of aquatic systems are also characterized as having kinds of substrates, such as rock substrate, clay substrate, etc. Substrate is also used to describe something on which an enzyme acts.

A surface on which something grows or is attached. As in "barnacles grow on hard substrates." The bottoms of rivers and lakes usually are described as having a kind of substrate, such as rock substrate, clay substrate, etc.

See Also: substratum

Substance upon which an organism grows or lives


the underside of a body of a jellyfish.


living in residential areas on the outskirts of large cities or towns.


adapted for sucking or clinging by suction, or having parts or organs that are adapted for sucking or clinging.


The Ganges, Brahmaputra and Meghna River come together in Bangladesh to form a 10,000 sq km (3850 sq mi) delta, the largest in the world. At the edge of the delta is the Sundarbans, the world's largest mangrove forest.


A super-group forms when two or more groups of animals of a species (e.g. Drill (Mandrillus leucophaeus) or Mandrill (Mandrillus sphinx)) come together for short periods.


a wetland area that may be permanently or intermittently covered in water, often dominated by woody vegetation.


a type of canal system in certain sponges (Phylum Porifera).


an organism involved in a symbiotic (see symbiosis) relationship.


an intimate relationship between two different species. The symbiont (see symbiont) always benefits and the host (other member of the symbiosis) may benefit (called a mutualism), not be affected (called a commensalism), or may be harmed (predation or parasitism).


Relating to two or more animals whose geographical ranges overlap (compare Allopatric).

synapsid skull

The skull has one pair of openings, located in a lateral temporal position, through which the jaw muscles attach. Synapomorphy of the mammals and close mammalian relatives (Pelycosaurs, "Early Therapsids", and Cynodonts).


a cell that is formed through the fusion of multiple cells, resulting in a multinucleate mass of cytoplasm within the boundaries of a single cell. Syncitial: cell membranes are not present to separate nuclei.


one of two or more scientific names that have been applied to a given taxon (species, genus, family, etc.). A synonym is a name by which a taxon was previously known, but is no longer considered the valid name.

See Also: taxon; taxonomy

The science of classifying organisms based on their evolutionary relationships, most often using shared-derived (synapomorphic) characters such as genetic, morphological, physiological, and behavioral characters.

See Also: phylogenetic; taxonomy