Zoology: Invertebrate Diversity, Anatomy, and Evolution

Comprehensive practice flashcards reviewing all key terminology, anatomical structures, taxonomic classes, and evolutionary adaptations across the nine invertebrate zoology lecture modules.

Panarthropoda

Clade uniting Onychophora, Tardigrada, and Arthropoda, characterized by a reduced coelom, ventrolateral appendages, a hemocoel with open circulation, and paired walking appendages.

Phylum Onychophora

Phylum of caterpillar-like velvet worms with suppressed external segmentation, lobelike legs with pads and claws, an open circulatory system, a tracheal system, and slime glands.

Slime Glands (Onychophora)

Specialized glands in velvet worms that shoot sticky secretions from unique oral papillae to ensnare prey.

Phylum Tardigrada

Phylum of microscopic water bears with elongated, unsegmented bodies, stubby unjointed legs bearing 4-8 claws, a Malpighian tubule excretory system, and an open circulatory system.

Buccal Stylets

Sharp piercing structures situated within the pharynx of tardigrades used to suck plant or animal juices.

Cryptobiosis

State of suspended animation in tardigrades where metabolism ceases during harsh conditions, accompanied by the loss of up to 97% of body water.

Tun

The shriveled, desiccated resting body form assumed by a tardigrade entering cryptobiosis, capable of surviving extreme cold, heat, pressure, and radiation for decades.

Tagmata

Specialized functional body regions in arthropods formed by the evolutionary fusion of adjacent segments.

Tagmosis

The evolutionary process of segment fusion that gives rise to specialized functional body regions (tagmata) in arthropods.

Epicuticle

The outermost, waxy non-cellular layer of the arthropod exoskeleton secreted by the epidermis to prevent water loss (desiccation).

Procuticle

The inner, thicker cuticular layer of the arthropod exoskeleton composed of protein and chitin, often impregnated with $CaCO_3$.

Chitin

A tough, resistant polysaccharide derived from glucose that constitutes the primary structural component of the arthropod exoskeleton.

Ecdysis

The periodic shedding or molting of the nonliving cuticle that allows an arthropod to grow into a larger skeleton.

Pre-ecdysis

The initial molting stage where the old procuticle detaches from the epidermis, a new epicuticle is secreted, and molting fluid dissolves and reabsorbs the old endocuticle.

Post-ecdysis

The final stage of molting where the newly secreted cuticle is stretched, unfolded, and expanded, followed by the secretion of new endocuticle.

Chelicerae

Pointed, grasping anterior mouthparts characteristic of chelicerates that end in fangs used to pierce and grasp food.

Ommatidia

The individual visual receptor units that compose the compound eyes of arthropods.

Subphylum Chelicerata

Arthropod subphylum characterized by two tagmata (cephalothorax and abdomen), chelicerae, one pair of pedipalps, four pairs of legs, and an absence of antennae.

Pedipalps

The second pair of cephalothoracic appendages in chelicerates, modified for food handling, sensory perception, defense, or sperm transfer in males.

Class Merostomata

Arthropod class comprising horseshoe crabs, possessing book gills, copper-based blue blood, and fossils dating back approximately 480 million years.

Class Pycnogonida

Marine chelicerate class (sea spiders) possessing four pairs of long walking legs, a suctorial proboscis, a greatly reduced abdomen, and male ovigers.

Ovigers

Specialized paired leg appendages in male pycnogonids (sea spiders) used to carry and brood egg masses.

Order Araneae

Chelicerate order of spiders characterized by venomous fangs on chelicerae, eight simple eyes, pedipalps, silk glands with spinnerets, and predaceous habits.

Spinnerets

Abdominal appendages in spiders through which liquid protein from silk glands is drawn and extruded as solid silk threads.

Gaius villosus

Australian trapdoor spider species subject to a 50+ year wild population study, exhibiting extreme longevity and prolonged female maternal care.

Number 16

A wild female Gaius villosus trapdoor spider in Western Australia that survived to age 43 before dying from a parasitic wasp sting.

Dr. Barbara York Main

Australian zoologist known as the 'Lady of the Spiders' who described over 70 spider taxa and conducted the 40+ year field study on Gaius villosus.

Order Scorpiones

Arachnid order characterized by large chelate pedipalps, small chelicerae, ventral sensory pectines, and a segmented tail terminating in a venomous sting.

Pectines

Ventral, comb-like sensory organs on the abdomen of scorpions used to detect vibrations and substrate characteristics.

Order Solifugae

Arachnid order known as camel spiders, nonvenomous and equipped with massive, tearing chelicerae adapted for shredding desert prey.

Order Opiliones

Arachnid order (harvestmen/daddy longlegs) characterized by a rounded body with broadly joined cephalothorax and abdomen without a pedicel, two eyes on a tubercle, and nonvenomous habits.

Order Acari

Arachnid order comprising mites and ticks, possessing complete fusion of body tagmata under a single dorsal shield and anterior mouthparts on a capitulum.

Capitulum

The anterior mouthpart-bearing projection on the body of mites and ticks (Order Acari).

Subphylum Myriapoda

Arthropod subphylum characterized by two tagmata (head and multi-segmented trunk), paired trunk appendages, a tracheal respiratory system, and Malpighian tubules.

Class Chilopoda

Myriapod class of centipedes, featuring flattened bodies, one pair of walking legs per segment, and venomous maxillipeds (poison claws) for predation.

Class Diplopoda

Myriapod class of millipedes, featuring subcylindrical bodies, two pairs of walking legs per abdominal segment, and defensive repugnatorial glands.

Repugnatorial Glands

Defensive glands along the sides of millipedes (Class Diplopoda) that secrete toxic or foul-smelling repellent fluids.

Carapace (Crustacea)

A cuticular dorsal covering formed by the fusion of the head exoskeleton with several thoracic and abdominal segments in crustaceans.

Antennules

The smaller first pair of sensory antennae located on the head of crustaceans.

Biramous Appendages

Two-branched appendages typical of crustaceans, consisting of a basal protopod that splits into an inner endopod and an outer exopod.

Antennal Glands

Paired excretory and osmoregulatory organs situated at the base of the second antennae in crustaceans (also called green glands).

Nauplius Larva

The ancestral free-swimming crustacean larva characterized by an unsegmented body, three pairs of appendages, and a single median light-sensing eye.

Class Branchiopoda

Crustacean class (water fleas, brine shrimp) characterized by flattened, leaf-like legs (phyllopodia) used for respiration, filter feeding, and swimming.

Phyllopodia

Flattened, leaf-like appendages in branchiopod crustaceans that serve simultaneously as gills, swimming paddles, and suspension-feeding apparatuses.

Vernal Pools

Ephemeral seasonal freshwater wetlands formed entirely by precipitation, lacking permanent inlets or outlets and fish predators.

Branchinecta lynchi

The vernal pool fairy shrimp, a federally threatened branchiopod endemic to temporary seasonal wetlands in California and Oregon.

Class Copepoda

Abundant aquatic crustacean class possessing prominent first antennae, swimming biramous thoracic legs, a forked tail, and a single median naupliar eye.

Calanus

A widely distributed, ecologically dominant copepod genus serving as a major primary consumer link in commercial marine food chains.

Class Thecostraca

Crustacean class of barnacles whose adults are sessile, enclosed within a mantle that secretes calcareous plates, and feed via setose thoracic cirri.

Cirri (Thecostraca)

Feathery thoracic legs lined with hair-like setae used by sessile barnacles to filter food particles out of the water column.

Cypris

The bivalved post-naupliar larval stage of barnacles specialized for swimming, locating substrate, and cementing its head to a surface.

Order Isopoda

Malacostracan crustacean order characterized by a dorsoventrally flattened oval body, lack of a carapace, and direct development.

Orthione griffenis

An invasive Asian bopyrid isopod that parasitizes native mud shrimp along the Pacific coast of North America by blood-sucking in their gill cavities.

Order Amphipoda

Malacostracan crustacean order of laterally flattened detritivores and scavengers that lack a carapace and curve into a 'C' shape.

Order Euphausiacea

Malacostracan order comprising krill, pelagic shrimp-like crustaceans with thoracic filtering baskets that make up the largest biomass of any marine animal group.

Order Stomatopoda

Malacostracan order of predatory mantis shrimp possessing trinocular compound eyes and raptorial second thoracic legs adapted for smashing or spearing prey.

Order Decapoda

Crustacean order (crabs, lobsters, shrimp) possessing ten walking legs (five pairs), a carapace covering the entire thorax, and large anterior chelae.

Rostrum (Decapoda)

An anterior, forward-projecting cuticular extension of the carapace that extends over the head and compound eyes of decapod crustaceans.

Lybia tessellata

The boxer crab, a decapod that carries living sea anemones in its chelae for defensive stinging and food collection in a mutualistic symbiosis.

Carcinization

The convergent evolutionary phenomenon in which non-crab decapod crustaceans independently evolve a crab-like body form at least six separate times.

Biomimetics

The application of biological designs, structural ratios, and physiological processes to engineering, robotics, and synthetic materials design.

Subphylum Hexapoda

Arthropod subphylum characterized by six uniramous walking legs, a tracheal respiratory system, and three tagmata: head, thorax, and abdomen.

Thorax (Hexapoda)

The intermediate three-segmented tagma of insects (prothorax, mesothorax, metathorax) that carries three pairs of legs and up to two pairs of wings.

Prolegs

Fleshy, unjointed abdominal cuticular extensions with suckers found in insect larvae (such as caterpillars), distinct from true thoracic legs.

Direct Flight Muscles

Insect flight muscles that attach directly to the wing bases to control wing stroke angle and direction.

Indirect Flight Muscles

Flight muscles that attach to and distort the thoracic cuticular box to drive wing elevation and depression without connecting to the wings.

Spiracles

Valved cuticular pores along the lateral margins of the insect thorax and abdomen that admit atmospheric oxygen into the tracheal system.

Tracheae (Hexapoda)

An extensive network of chitin-lined, branching internal tubes in insects that delivers oxygen directly from spiracles to tissues.

Tracheoles

Microscopic, fluid-filled terminal branchlets of the insect tracheal system that contact individual cells for gas exchange.

Malpighian Tubules (Hexapoda)

Slender excretory tubes floating in insect hemolymph that extract nitrogenous wastes and excrete them as dry uric acid crystals with feces.

Instar

The developmental life stage of an insect between successive molting events (ecdyses).

Ametabolous Metamorphosis

Direct development in primitive wingless insects (e.g., silverfish) where newly hatched juveniles look identical to adults except for size and sexual maturity.

Hemimetabolous Metamorphosis

Incomplete or gradual metamorphosis in insects where wing pads develop externally across successive nymphal instars before the final molt.

Holometabolous Metamorphosis

Complete metamorphosis in insects passing through egg, feeding larva, quiescent pupa, and adult, completely reorganizing bodily tissues.

Class Entognatha

Hexapod class (including springtails) characterized by having the bases of mouthparts enclosed within a deep facial pocket in the head capsule.

Class Insecta

Hexapod class characterized by ectognathous mouthparts (projecting outside the head capsule) and three thoracic segments typically carrying two pairs of wings.

Clade Paleoptera

Ancestral winged insect group comprising dragonflies, damselflies, and mayflies that cannot fold their wings back flat over the abdomen.

Order Odonata

Paleopteran insect order comprising dragonflies and damselflies, featuring large multi-faceted compound eyes, agile flight, and predatory aquatic nymphs.

Order Ephemeroptera

Paleopteran insect order of mayflies, possessing delicate veined wings, aquatic nymphs, and short-lived adult stages with vestigial mouthparts.

Clade Neoptera

Advanced winged insect lineage possessing a cuticular flexure mechanism allowing the wings to fold roof-like over the abdomen when at rest.

Superorder Hemimetabola

Neopteran insect division exhibiting incomplete metamorphosis, including grasshoppers (Orthoptera), mantids (Mantodea), and true bugs (Hemiptera).

Superorder Holometabola

Neopteran insect division exhibiting complete metamorphosis with pupal reconstruction, including beetles, flies, butterflies, and wasps.

Order Coleoptera

The beetles; the largest animal order (over 250,000 described species), characterized by hardened, armor-like forewings called elytra.

Order Hymenoptera

Insect order containing bees, ants, and wasps, characterized by two pairs of membranous wings, frequent eusociality, and female ovipositors modified as stingers.

Eusociality

Advanced animal social organization defined by cooperative brood care, overlapping adult generations, and reproductive division into fertile and sterile castes.

Corbicula

The specialized, hair-fringed pollen basket on the hind tibia of worker honeybees used to store compacted pollen pellets.

Royal Jelly

Nutrient-rich secretion produced by worker nurse bees that, when fed continuously to a female larva, triggers its development into a fertile queen.

Waggle Dance

A figure-eight pattern performed by honeybee scouts on hive combs to communicate the distance and compass direction to a nectar source.

Colony Collapse Disorder

Syndrome where worker bees abruptly desert their hive and queen, linked to an interaction of parasitic mites, pesticides, pathogens, and habitat loss.

Linguamyrmex vladi

An extinct Cretaceous 'hell ant' preserved in 98-million-year-old amber, featuring upward-striking scythe-like mandibles and a metal-reinforced cranial horn.

Fungus-farming Ants

Lineage of ants (such as leafcutters Atta and Acromyrmex) that have cultivated completely domesticated monoculture fungi for 66 million years.

Order Lepidoptera

Insect order containing moths and butterflies, characterized by broad wings covered in microscopic overlapping pigmented scales and coiled sucking proboscises.

Danaus plexippus

The monarch butterfly, known for multi-thousand-mile winter migrations whose western North American population has declined by >99% since the 1980s.

Parasitoid

An organism whose developing juvenile feeds internally or externally on a single host organism, invariably killing the host upon completing development.

Cordyceps

Ascomycete fungal genus whose mycelium infects insects, manipulates their nervous system to optimize spore dispersal, and sprouts fruiting bodies from their heads.

Aposematic Coloration

Conspicuous bright warning colors displayed by toxic or unpalatable insects to signal their distastefulness to visual predators.

Cimex

Genus of wingless, dorsoventrally flattened blood-feeding parasitic true bugs (bedbugs) within Order Hemiptera.

Phylum Mollusca

Coelomate lophotrochozoan protostome phylum characterized ancestrally by a muscular head-foot, radula, mantle, mantle cavity, and calcareous shell.

Hypothetical Ancestral Mollusc (HAM)

A theoretical diagrammatic archetype demonstrating the primitive, unspecialized body plan from which all eight modern mollusc classes diverged.

Radula

A rasping, tongue-like ribbon of replaceable chitinous teeth supported by an odontophore, present in all molluscs except bivalves.