Glossary

The glossary below includes select terminology used here and it also includes other terms often associated with the description of aquatic invertebrates.

Abdomen - the third main division of the body; behind the head and thorax
Accessory flagellum - a small fingerlike projection or subantenna of the antenna, especially of amphipods
Anterior - in front; before
Apical - near or pertaining to the end of any structure, part of the structure that is farthest from the body; distal
Apicolateral - located apical and to the side
Basal - pertaining to the end of any structure that is nearest to the body; proximal
Bilobed - divided into two rounded parts (lobes)
Calcareous - resembling chalk or bone in texture; containing calcium
Carapace - the hardened part of some arthropods that spreads like a shield over several segments of the head and thorax
Carinae - elevated ridges or keels, often on a shell or exoskeleton
Caudal filament - threadlike projection at the end of the abdomen; like a tail
Cercus (pl. cerci) - a paired appendage of the last abdominal segment
Concentric - a growth pattern on the opercula of some gastropods, marked by a series of circles that lie entirely within each other; compare multispiral and paucispiral
Corneus - resembling horn in texture, slightly hardened by still pliable
Coxa - the basal segment of an arthropod leg
Creeping welt - a slightly raised, often darkened structure on dipteran larvae
Crochet - a small hook like organ
Cupule - a cup shaped organ, as on the antennae of some beetles (Coleoptera)
Detritus - disintegrated or broken up mineral or organic material
Dextral - the curvature of a gastropod shell when the opening is visible on the right when the spire is pointed up
Distal - near or toward the free end of any appendage; that part farthest from the body; apical
Dorsal - pertaining to, or situated on the back or top, especially of the thorax and abdomen
Dorsolateral - toward the top and side
Elytra - hardened shell-like mesothoraic wings of adult beetles (Coleoptera)
Femur - the leg section between the tibia and coxa of Arthropods, comparable to an upper arm or thigh
Flagellum - a small fingerlike or whip like projection
Furcula - the forked springtail of Collembola
Gill - any structure especially adapted for the exchange of dissolved gases between animal and a surrounding liquid
Glossae - a lobe or lobes front and center on the labium; in Plecoptera, the lobes are between the paraglossae
Hemelytra - the leathery mesothoraic wings of some Hemiptera
Labium - a lower mouthpart of an arthropod like a jaw or lip
Labrum - an upper mouthpart of an arthropod consisting of a single usually hinged plate above the mandibles
Lateral - feature or marking located on the side of a body or other structure
Lateral teeth - ridges on the inside edge of a bivalve shell, near the hinge and to the sides of the beak
Ligula - forming the ventral wall of an arthropod's oral cavity; the "lower lip"
Lobe - a rounded projection or protuberance
Mandibles - the first pair of jaws in insects
Maxillae - the second pair of jaws in insects
Mesocoxae - the basal segments of the middle legs
Mesonotum - the dorsal surface of the mesothorax
Mesotarsi - the tarsus of the middle legs
Mesothorax - the third or hind section of the thorax bearing the hind legs

Metathorax - the third or hind section of the thorax bearing the hind legs
Metatibiae - hind tibia
Molar lobe - the ridged or roughened grinding surface of the mandible
Multi spiral - a growth pattern on the opercula of some gastropods marked by several turns from the center to the edge; compare paucispiral and concentric
Notum - the dorsal surface of any thoracic segment
Operculate - having a lid or cover
Operculum - a lid or covering structure, like a door to an opening
Palpal lobes - the grasping pinchers at the end of the Odomata lower jaw
Palpus (pl. palpi) - tactile, usually segmented structure on the maxillae and labium
Papillae - fleshy protuberances
Paraglossa (pl. paraglossae) - lateral lobe of the labium
Paucispiral - a growth pattern on the opercula of some gastropods marked by few turns from the center to the edge; compare multispiral and concentric
Perphyton - algae and associated organisms that live attached to underwater surfaces
Procoxae - the basal segments of the front legs
Posterior - behind; opposite of anterior
Prementum - distal portion of the lower jaw of an odonata
Proleg - any projection appendage that serves for support locomotion or attachment
Pronotum - the upper or top part of the prothorax
Protarsus (pl. protarsi) front foot, occurring on legs arising from first thoracic segment
Prostheca - a mandibular sclerite set with hair
Prothorax - the first thoraic is segment closes to the head
Protibia (pl. protibiae) tibia of the foreleg
Protrochantin - on the front leg, a small, forward projecting sclerite on the trochanter (the segment between the coxa and femur)
Rostrum - a beak or beaklike mouthpart
Sclerite - a hardened area of an insect body wall, usually surrounded by softer membranes
Scutellum - in adult coleopterans and Hemiptera, the triangular sclerite between the base of the elytra or hemelytra
Seta (pl. setae) - hair like projection
Sinistral - the curvature of a gastropod shell where the opening is seen on the left when the spire is pointed up
Spiracle - an opening to the internal respiratory system usually at the sides or end of the abdomen of insects
Sternum (pl. sterna) - the entire ventral portion of a thoracic or abdominal segment
Tarsus (pl. tarsi) - the leg segment or segments at the apex of the tibia usually bearing a claw
Telson - the most posterior segment of a crustacean
Thoracic - of or pertaining to the thorax
Thorax - middle portion of the body between the head and abdomen, consisting of three segments (prothorax, mesothorax, and metathorax), each of which bears a pair of articulated legs
Tibia - the segment of an arthropod leg, between the femur and tarsus, comparable to a shin or forearm of human anatomy
Tubercles - small bumps or pimple like structures
Ventral - toward the lower surface when the body is in normal walking position; opposite of dorsal
Verrucae - wart like elevations bearing several too many setae pointing in different directions
Ventrolateral - on the lower surface and to one side of the midline
Wingpads - the developing wing of an immature insect