Invertebrate Zoology, Animal Evolution, and Fungal Diversity

Vocabulary practice flashcards covering animal development, sponge anatomy, cnidarians, lophotrochozoans, ecdysozoans, early Earth history, and fungal biology based on lecture slides.

Cephalopodium

The integrated body region in cephalopods where the head and modified foot lie close together, consisting of anterior foot extensions (arms and tentacles) surrounding the mouth and a posterior foot modification (funnel).

Funnel (Cephalopoda)

A muscular tube derived from the posterior foot that ejects water from the mantle cavity through muscular contraction to achieve directional jet propulsion.

Nautilus

A cephalopod taxon belonging to Nautilida that retains an external, chambered shell containing gas-filled septa and a siphuncle functioning as a hydrostatic buoyancy device.

Decabrachia

A cephalopod lineage possessing 10 arms, an internal shell, ink sacs, and specialized cells used for camouflage and signaling.

Octobrachia

A cephalopod group possessing 8 arms and no shell, characterized by exceptional camouflage capabilities and limited swimming ability relative to squid.

Clitellum

A glandular skin region in clitellate annelids (Oligochaeta and Hirudinea) that secretes a protein-rich cocoon for eggs, assists in burrow lining formation, and functions in mating.

Prostomium

The anterior-most region of an annelid that houses chemo-, light-, and mechanoreceptors, antenna-like palps, and the brain, but lacks most other internal organs.

Metameres

Repeated linear segments in annelids, each ancestrally containing its own ganglia, excretory organs, reproductive structures, a pair of parapodia, and chaetae.

Chaetae (Setae)

Chitinous, hair-like bristles located on each annelid segment that can be extended or retracted to assist in movement.

Haementheria ghilianii

A species of leech (Hirudinea) measuring up to $17\,\text{inches}$ that can survive for several months without feeding by storing nucleated red blood cell-depleted blood in its gut with symbiotic bacterial antibiotics.

Ecdysis

The periodic shedding or molting of the non-living outer cuticle layer secreted by the epidermis, serving as the defining synapomorphy of Ecdysozoa.

Eutely

A developmental state in which every adult individual of a species consists of a constant, fixed number of cells, characteristic of Nematoda and Tardigrada.

Dracunculus medinensis

A parasitic roundworm (Guinea worm) that infects humans through ingestion of water fleas (copepods) containing $L3$ larvae; the adult female emerges approximately one year later through a painful skin blister.

Wuchereria bancrofti

A parasitic nematode whose adults inhabit human lymph nodes causing blockage and swelling; female worms release microfilariae that circulate in peripheral blood at dusk and dawn to be transmitted by mosquitoes.

Onychophora

A phylum of pan-arthropods known as velvet worms with segmented bodies, paired unjointed lobopod appendages, and oral papillae that shoot adhesive slime to capture prey.

Tun State

A cryptobiotic desiccated resting state entered by tardigrades (moss piglets) allowing them to survive extreme pressures, X-rays, radiation, and temperatures down to 1^\n\circ\text{F} for seven months.

Cephalon (Arthropoda)

The anterior body tagma formed by the developmental fusion of 6 segments, typically bearing sensory antennae, mouthparts, one pair of compound eyes, and 4 median eyes.

Chelicerae

The first, most anterior pair of appendicular feeding structures (often pincer-like or scissor-like) that characterizes the subphylum Chelicerata.

Prosoma

The anterior body region (cephalothorax) of chelicerates that integrates sensory organs, the brain, mouthparts, and walking legs.

Opisthosoma

The posterior tagma (abdomen) of chelicerates that houses internal organs such as the respiratory structures (book lungs or book gills) and the heart.

Radula

A rasping, chitinous ribbon of teeth unique to molluscs (lost secondarily in bivalves) supported by an odontophore and used to scrape or slice food particles.

Mantle (Mollusca)

A dorsal epidermal fold covering the visceral mass that secretes the calcareous shell and forms the mantle cavity containing the gills and anus.

Polyplacophora

A class of marine molluscs (chitons) with a dorsoventrally flattened body, an encircling mantle girdle, and an armored shell composed of 8 overlapping articulating plates.

Torsion

A developmental process in gastropods where differential muscle growth rotates the visceral mass and mantle cavity 180^\n\circ, positioning the gills and anus directly above the head.

Operculum

A corneous or calcareous disc attached to the dorsal foot of many gastropods that seals the aperture of the shell when the soft body is retracted inside.

Love Dart

A sharp calcium carbonate structure covered in hormone-rich mucus shot by hermaphroditic terrestrial snails during courtship to suppress the digestion of transferred sperm in the recipient's bursa copulatrix.

Cnidosac

A specialized terminal chamber at the tip of the cerata (digestive diverticula) of nudibranchs where undischarged nematocysts sequestered from consumed cnidarians are stored for defensive kleptocnidy.

Umbo

The prominent, oldest dorsal region of a bivalve valve around which subsequent shell concentric growth layers are secreted by the mantle.

Periostracum

The outer organic protein layer of a mollusc shell secreted first by a mantle groove fold to provide physical stability and protect the underlying calcium carbonate layers from chemical erosion.

Byssus Threads

Tough collagenous anchoring filaments secreted by a specialized gland in the foot of certain sessile bivalves (such as mussels) to adhere firmly to hard marine substrates.

Anthozoa

A class of entirely marine cnidarians comprising corals, sea anemones, and sea fans that exist exclusively as polyps with no medusa stage in their life history.

Zooxanthellae

Symbiotic photosynthetic dinoflagellates (such as Symbiodinium sp.) residing intracellularly in the gastrodermis of reef-building corals that produce nutrients and give corals their distinctive color.

Corallite

The calcareous skeletal cup secreted by the basal epidermis of a coral polyp through the active transport of $Ca^{2+}$ and $HCO_3^-$ while pumping out $H^+$ to precipitate $CaCO_3$.

Cubozoa

A class of cnidarians known as box jellyfish (such as Chironex fleckeri) characterized by a box-shaped medusa bell, complex rhopalial eyes with lenses, and extremely potent neurotoxic venoms.

Scolex

The specialized anterior attachment organ of a tapeworm (Cestoda) bearing suckers, hooks, or grooves used to anchor the parasite firmly to the vertebrate host's intestinal wall.

Proglottids

Reproductive segment-like units continuously budded from the neck of a tapeworm strobila, each containing independent sets of male and female reproductive organs.

Protonephridia

A network of branching excretory tubules capped by ciliated flame cells found in flatworms, primarily functioning in osmoregulation and fluid balance by driving water into excretory pores.

Architomy

A form of asexual reproduction in flatworms in which the organism spontaneously splits into two fragments prior to the differentiation of lost organ systems, followed by cellular regeneration.

Paratomy

A form of asexual fission in flatworms where budding occurs perpendicular to the anterior-posterior axis, with complete structural differentiation occurring before separation.

Schistosoma

A genus of dioecious parasitic flukes causing bilharzia (schistosomiasis), in which the larger male permanently clasps the slender female in its ventral gynecophoric canal while inhabiting blood vessels near the bladder or intestines.

Choanocytes

Collar cells lining the internal spongocoel or flagellated chambers of sponges, featuring a central flagellum surrounded by a microvilli collar to generate water currents and ingest food via phagocytosis.

Amoebocytes

Mobile, amoeboid cells found in the sponge mesohyl responsible for distributing digested nutrients, producing gametes, and secreting mineralized spicules or spongin fibers.

Mesohyl

The gelatinous, non-cellular proteinaceous matrix between the outer pinacoderm and inner choanoderm of sponges that contains amoebocytes and structural spicules.

Gemmules

Internal, dormant clusters of sponge amoebocytes enclosed within a protective spicule-reinforced coat, formed primarily by freshwater sponges to survive adverse environmental conditions.

Cnidocyte

The stinging cell unique to Cnidaria containing an explosive intracellular organelle (nematocyst) that discharges a venom-injecting barbed thread upon mechanical or chemical stimulation.

Mesoglea

The non-cellular, jelly-like gelatinous layer sandwiched between the outer epidermis and the inner gastrodermis in cnidarians, functioning as a flexible hydrostatic skeleton.

Rhopalium

A sensory structure situated along the bell margin of scyphozoan and cubozoan medusae containing statocysts for equilibrium and photoreceptors for light perception.

Physalia physalis

The Portuguese Man-of-War, a pleustonic colonial hydrozoan composed of specialized, morphologically distinct zooids functioning collectively as a single organism.

Pneumatophore

The gas-filled, sail-like modified polyp that acts as a surface flotation device in siphonophores like the Portuguese Man-of-War.

Dactylozooid

A defensive and food-capturing specialized polyp in colonial hydrozoans, bearing heavily armed, stinging tentacles that can extend up to $50\,\text{m}$ in length.

Protostome Development

An embryonic development pattern characterized by spiral and determinate cleavage, schizocoelous coelom formation from splits within solid mesodermal masses, and the blastopore developing into the mouth.

Deuterostome Development

An embryonic development pattern characterized by radial and indeterminate cleavage, enterocoelous coelom formation from archenteron outpouchings, and the blastopore developing into the anus.

Pseudocoelomate

An animal body plan possessing a fluid-filled body cavity that is only partially lined with mesoderm, situated directly between the endodermal gut and ectodermal body wall.

Stromatolites

Layered accretionary rock structures formed in shallow water by the trapping, binding, and cementation of sedimentary grains by photosynthetic microbial mats dominated by cyanobacteria.

Great Oxidation Event

A geological interval occurring approximately $2.5 - 2.4\,\text{billion years ago}$ marked by the rapid accumulation of biogenic oxygen in Earth's atmosphere, leading to ozone formation and severe greenhouse gas depletion.

Ediacaran Fauna

An assemblage of soft-bodied, predominantly benthic multicellular organisms ($570 - 540\,\text{million years ago}$) discovered in the Ediacara Hills of South Australia that largely disappeared prior to the Cambrian.

Dickinsonia

An enigmatic, ribbed, flat Ediacaran fossil confirmed as an early animal through preserved organic geochemical biomarkers consisting of cholesteroids.

Cambrian Explosion

The geologically rapid radiation of complex bilaterian animals beginning roughly $540\,\text{million years ago}$, marked by mineralized exoskeletons, compound limbs, advanced predatory adaptations, and the appearance of modern phyla.

HOX Genes

A highly conserved suite of homeobox regulatory genes unique to animals that dictate segment identity and spatial body pattern organization along the anterior-posterior axis.

PAX6

A universal master control gene directing eye morphogenesis that is functionally interchangeable across animals, capable of directing ectopic eye formation in fruit flies when induced with human orthologs.

Plasmogamy

The cellular fusion of cytoplasm from two compatible fungal hyphae without immediate nuclear fusion, yielding a heterokaryotic or dikaryotic stage ($n + n$).

Karyogamy

The fusion of two distinct haploid nuclei in a fungal cell, producing a transient diploid ($2n$) zygotic nucleus that subsequently undergoes meiosis.

Zoospores (Chytridiomycota)

Flagellated, motile haploid or diploid fungal spores unique to the phylum Chytridiomycota that require water films to swim toward substrates or hosts.

Zygosporangium

A robust, thick-walled, multinucleate sexual resting structure characteristic of Zygomycetes produced after plasmogamy that remains dormant until conditions favor karyogamy and meiosis.

Arbuscules

Intricately branched fungal hyphal structures formed within plant root cortical cells by Glomeromycota that mediate reciprocal nutrient exchange of soil minerals for host photosynthetic carbon.

Ascus

A microscopic, sac-like sexual sporangium defining the Ascomycota within which karyogamy and meiosis occur, followed by a single mitotic division to yield 8 haploid ascospores.

Ophiocordyceps unilateralis

An entomopathogenic ascomycete that behaviorally manipulates carpenter ants (Camponotus leonardi) to leave their canopy colony, descend to an exact height of $25\,\text{cm}$, and clamp their mandibles into a leaf vein before fungal fruiting body eruption.

Pseudogymnoascus destructans

A psychrophilic ascomycete fungus that causes white-nose syndrome in hibernating North American bats by invading their cutaneous epidermal tissues around the muzzle and wings.

Basidium

A club-shaped sexual sporangium produced on the basidiocarp of Basidiomycota upon which nuclear fusion and meiosis produce 4 external haploid basidiospores on sterigmata.

Lichen

A mutualistic symbiotic association consisting of a structural fungal partner (mycobiont, typically an ascomycete) housing a photosynthetic alga or cyanobacterium (photobiont).