Definitions

Daddy long legs Tipulidae
Daddy long legs spider Pholcidae
Damselfly Zygoptera
Dance fly Empididae
Darwinism The view of evolution as expressed by Charles Darwin, i.e. that evolution occurs by natural selection acting on random variation found in organisms, and resulting in the survival of the fittest.
Death rate Mortality. The number/percentage of deaths in a population over a given time.
Decapods The group of crustaceans which includes crabs, lobsters, prawns and shrimps.
Definitive host The host in which sexual reproduction takes place. Or in cases where there is no sexual reproduction, the host in which the parasite/symbiont becomes mature and reproduces.
Demography the study of statistics relating to births and deaths in populations
Demospongiae Class of sponges (Porifera) that contains the bath sponge.
Density the number of individuals per unit area
Denticle a tooth-like process on the cuticle
Depauperate Impoverished; having few species.
Deposit feeder an animal that feeds on particles of organic matter that drift downwards through the water to settle on the bottom.
Dermaptera earwig
Dermestidae carpet beetle, skin beetle
Desiccation the removal of water, the process of drying
Detritus dead organic matter
Detrivore an animal that eats dead plant and animal matter
Dextral rotating to the right, as in snail shells. The opposite is sinistral.
Diadromous Migrating between fresh and sea water
Dichotomy a division into 2 parts or categories
Dictyoptera The order of Insects containing the cockroaches and mantids. Some authorities now separate these into 2 orders.
Diapause A period of arrested development found mainly in insects, in which physiological activity is very low, and the animal is highly resistant to unfavourable external conditions.
Diet selection An animal will usually rank items in terms of profitability. Most profitable are those with a high size and/or quality : search, handling time ratio
Diffusion The spontaneous tendency of a substance to move down its concentration gradient from a more concentrated to a less concentrated area
Digestion the process of breaking down food into molecules small enough for the body to absorb
Dimorphism The existence within a species of 2 distinct body forms differing in colour, or sex, or size, etc.
Diploid Having a double set of chromosomes
Diplopoda Millipedes
Diptera true flies
Disjunct Distinctly separate. Used when describing populations which are so separated from each other as to prohibit interbreeding, and therefore gene flow.
Dispersal The spread outwards of organisms from their point of origin or release. The extension of range of a population or species.
Display A behaviour or signal which conveys information, e.g. wolf spiders signalling with their palps before mating.
Disruptive colouration colouring making it difficult for a predator to recognise the whole animal - as seen in many butterflies and moths.
Distal at the furthest end from the attachment of an appendage - opposite of proximal
Diurnal active during the day
Diversity The number of species in a community, also known as species richness. The measure of the number of species and their relative abundance in a community.
DNA Deoxyribonucleic acid
Dominance hierarchy a social ranking, formed through agonistic behaviour, in which individuals are associated with each other so that some have greater access to resources than others.
Dorsal of or belonging to the back
Dragonfly Odonata, ansioptera
Drone the male bee hatched from an unfertilized egg
Drosophilidae fruit fly, vinegar fly
Dung beetle a beetle in the Scarabaeidae family.
Dytiscidae A family of water beetles. Both larvae and adults are carnivorous, the adults are usually strong swimmers.
Earthworm A worm in the Oligochaeta Class of the Phylum Annelida.
Earwig An insect in the Dermaptera Order
Ecdysis moulting of cuticle to increase body size, e.g. in crustaceans. Normally it is hormonally controlled.
Ecdysone The hormone in insects and crustaceans that stimulates ecdysis.
Echinoderms A phylum of animals including starfish, brittle stars, sea urchins, etc. Echinoderm - spiny skin.
Echinoidea sea urchins, heart urchins, sand dollars.
Echiura spoon worms
Ecological isolation the prevention of interbreeding between population in the same area because of ecological barriers
Ecology the study of how organisms interact with their environment
Ecosystem a collection of species living in the same habitat together with their physical surroundings
Ectotherms Animals that must use environmental energy and behavioural adaptations to regulate their body temperature. Cold-blooded animals, e.g. most invertebrates, reptiles and amphibians
Ectoparasite A parasite that lives on the outside of its host. Opposite is endoparasite.
Elateridae Click beetles, skipjack beetles
Elbowed antennae aka geniculate antennae; antennae bent at an angle near the middle, as seen in bumblebees
Elytra the hardened fore wings of beetles. They serve as covers for the hind wings
Embioptera Webspinners
Emigration the movement of an individual or a group out of a population or area.
Empididae dance flies
Endemic A species which is encountered only in a given area or region, e.g. Primula scotica is endemic to Scotland.
Endoparasite A parasite that lives within the body of its host. Opposite is ecto parasite.
Endopterygote An insect in which the wing buds develop internally, e.g. beetles
Endoskeleton a skeleton formed within the body - like the human skeleton. Opposite is exoskeleton.
Endotherms Animals that use metabolic energy to raise their body temperature, e.g. bumblebees, humans.
Energy flow The passage of energy through an organism, population or system; the passage of energy through a food chain or food web.
Epigyne in spiders and other female arachnids, the external structure of the reproductive opening, seen only in mature females
Entomogamous of a flower pollinated by insects
Entomology the study of insects
Entomophaguos feeding on insects, insectivorous
Entomophilous pollinated by and/or dispersed by insects
Enzyme A protein that turns on vital functions in the cell; a chemical messenger or catalyst.
Ephemeroptera Mayflies
Epidaemic used of a disease which affects a high proportion of the population and spreads over a wide area.
Epidermis the outmost cellular body covering
Epithelial cells Cover external surfaces and line the digestive tract and connecting structures. They are often flat in shape.
Epoch A major interval of geological time. An event or time marking the beginning of a new phase of development.
Era A major interval of geological time, e.g. the Precambrian.
Erosion The wearing away or weathering of land surfaces, e.g. by water, wind etc.
Errant moving freely. Opposite is sedentary.
Essential element A chemical element which is essential to the life of the organism.
Ethnozoology The study of the uses of animals and animal products by the races of man.
Ethology the study of how animals behave in their natural environment
Eukaryote An organism with cells that have a discrete nucleus containing the genetic material.
Eumenidae A family of solitary wasps also known as the mason or potter wasps
Euryhaline able to tolerate a wide range of seawater concentrations
Eusocial Bees and wasps in a colony of adults of two or more generations, composed of an egg laying queen and her daughters.
Eutely A fixed number of cells or nuclei in mature adult forms, as in some rotifers, acanthocephalans and nematodes..
Eutrophication Over enrichment of water with nutrients, resulting in a population explosion of organisms and a reduction of oxygen.
Eutrophy The pollination of certain flowers by specialised insects.
Eversible capable of being turned inside-out
Evolution All the changes that have transformed life from its beginnings to the diversity we see today.
Evolutionary biology The science of evolution, ecology, behaviour and systematics.
Excretion disposal of the nitrogen-containing waste products of metabolism
Exopterygote an insect in which the wing buds develop externally, enlarging at each nymphal instar, e.g. in bugs.
Exoskeleton The horny outer shell which encloses and protects the body and to which the muscles are attached, as found in insects.
Exotic Alien; non-native; foreign; an introduced species.
Extant Existing or living at the present time. Opposite of extinct.
External fertilisation in reproduction a form of fertilisation that takes place outside the female's body - often in water.
Extinct No longer in existence;no longer living. Opposite of extant.
Extinction The disappearance of species or taxa from a habitat or biota.
Extra-oral digestion Digestion that takes place outside the organism, by secretion of salivary enzymes onto the food, with the resulting liquid digestive products being sucked up, e. g. in house flies and spiders.
Exude To ooze out, diffuse out.
Exuvium The cast off exoskeleton left by an arthropod after moulting. Most easily seen on a plant infested with aphids where the skins lie on the soil and leaves, also on the webs of successful spiders as the grow, and also here is a photograph of a woodlouse with its exuvium.
Eyespots simple eyes found on some annelids and flatworms. They enable the animal to distinguish light and dark, but little else.
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