Survey of the Animal Kingdom – Phylum Arthropoda (Exercise 39)

Vocabulary flashcards covering taxonomy, anatomy, and key physiological terms related to Arthropoda as presented in the Exercise 39 lecture notes.

Arthropoda

Largest animal phylum; characterized by segmented bodies, jointed appendages, and a chitinous exoskeleton

Exoskeleton

External skeleton made chiefly of chitin (often with calcium salts) that protects, supports, and limits water loss in arthropods

Chitin

Nitrogen-containing polysaccharide forming the principal component of an arthropod exoskeleton

Tagmata

Distinct body regions (e.g., head, thorax, abdomen) produced by fusion of segments in arthropods

Cephalothorax

Fused head and thoracic region of some arthropods; also called prosoma

Abdomen (Opisthosoma)

Posterior body region of many arthropods, following the cephalothorax

Chelicerae

First pair of claw-like feeding appendages in chelicerate arthropods, used for grasping or piercing prey

Pedipalps

Second pair of appendages in chelicerates; function in handling food, sensation, or reproduction

Carapace

Dorsal shield covering the cephalothorax of crustaceans and horseshoe crabs

Book gills

Respiratory structures of horseshoe crabs consisting of layered, page-like lamellae

Subphylum Chelicerata

Arthropods bearing chelicerae, lacking antennae; includes horseshoe crabs, spiders, scorpions, mites, ticks

Class Merostomata

Marine chelicerates known as horseshoe crabs (genus Limulus)

Limulus

Representative genus of horseshoe crabs in class Merostomata

Class Arachnida

Chelicerates with eight walking legs; includes spiders, scorpions, ticks, and mites

Subphylum Crustacea

Mostly aquatic arthropods with two pairs of antennae and biramous appendages

Class Malacostraca

Largest crustacean class; contains crabs, lobsters, shrimp, crayfish

Order Decapoda

Ten-legged malacostracans such as crabs, lobsters, shrimp, crayfish

Cambarus

Representative crayfish genus used in laboratory studies

Order Isopoda

Dorsoventrally flattened crustaceans (pillbugs, sowbugs, rolly-pollies)

Biramous appendage

Branched limb typical of crustaceans, with an inner endopod and outer exopod

Uniramous appendage

Single-branched limb characteristic of insects and myriapods

Cheliped

Large pincer-bearing first walking leg of many decapod crustaceans

Swimmerets (Pleopods)

Small abdominal appendages of crayfish used for swimming and, in males, sperm transfer

Uropod

Lateral flipper-like appendage forming part of the crayfish tail fan

Telson

Median terminal segment aiding in backward swimming in crustaceans

Gonopods

Modified anterior swimmerets of male crayfish that transfer sperm

Subphylum Myriapoda

Uniramous arthropods with many legs; includes centipedes and millipedes

Class Chilopoda

Fast-moving, carnivorous centipedes; one pair of legs per segment and poison claws

Maxillipeds (Poison claws)

First trunk appendages of centipedes used to inject venom into prey

Class Diplopoda

Herbivorous millipedes; two pairs of legs per apparent segment due to segment fusion

Subphylum Hexapoda

Six-legged arthropods; includes insects and their allies

Class Insecta

Hexapods with three tagmata, one pair of antennae, and (usually) wings

Romalea

Genus name of the lubber grasshopper dissected in lab

Tracheae

Internal air-filled tubes that deliver oxygen directly to tissues in insects

Spiracles

External openings on insect exoskeleton that connect to the tracheal system

Tympanum

Thin, hearing membrane located on the first abdominal segment of many grasshoppers

Malpighian tubules

Excretory and osmoregulatory organs that remove nitrogenous wastes from insect hemolymph

Compound eye

Multifaceted visual organ of arthropods composed of many ommatidia

Ocellus

Simple light-detecting eye spot found on the head of many insects

Labrum

Upper lip of an insect, forming the anterior margin of the mouth

Mandibles (Insect)

Jaw-like mouthparts used for biting or chewing food

Maxillae

Paired mouthparts located behind mandibles; assist in food manipulation

Labium

Lower lip of insects, formed by fused second maxillae, often bearing palps

Ovipositor

Egg-laying appendage at the posterior end of many female insects

Elytra

Hardened forewings of beetles that cover and protect the hind wings

Haltere

Small club-shaped hindwing of true flies (Diptera) functioning as a flight stabilizer

Hamuli

Tiny hooks that couple the fore- and hindwings of bees and wasps (Hymenoptera)

Analogous structures

Features with similar functions but independent evolutionary origins (e.g., spider chelicerae vs. crayfish mandibles)

Homologous structures

Features derived from a common ancestral structure, regardless of present function (e.g., jointed legs of spiders and crayfish)

Dichotomous key

Tool that identifies organisms by sequentially choosing between paired, contrasting statements