Animal Diversity: Porifera, Cnidarians, Ctenophores, and Lophotrochozoans

Comprehensive practice vocabulary flashcards covering the major animal clades from non-bilaterians (Porifera, Cnidaria, Ctenophora) to Lophotrochozoans (Platyhelminthes, Syndermata, Ectoprocts, Brachiopods, Molluscs, and Annelids) as described in the lecture notes.

Metazoa

The clade comprising all animals, which molecular data suggests shared a common ancestor approximately $770$ million years ago.

Porifera

Among the simplest animals and sister-group to all other animals, characterized by approximately $5500$ species that usually lack symmetry, true tissues, nerves, muscles, and a digestive system.

Choanocytes

An inner layer of cells in sponges that look like choanoflagellates and possess flagellae to pull water through pores for suspension feeding.

Mesohyl

A layer of gelatinous extracellular material located between the epidermis and choanocytes in sponges, containing spicules and spongin fibers.

Spicules

Tiny mineralized skeletal elements in sponges made of silicon dioxide ($SiO_2$) or calcium carbonate ($CaCO_3$) that help reduce predation.

Spongin

A protein that forms thick fibers in the mesohyl of sponges, acting as a skeletal element.

Osculum

The large opening in a sponge through which water is expelled after being filtered.

Cytarabine (Ara-C)

A nucleoside compound derived from a sponge that targets DNA polymerase and is used as a clinical treatment for cancer.

Eumetazoa

A clade of animals characterized by true tissues and either radial or bilateral symmetry, originating approximately $680$ million years ago.

Diploblastic

An organism having two embryonic tissue layers, the ectoderm and endoderm, which is characteristic of cnidarians and ctenophores.

Cnidaria

A phylum of approximately $10,000$ species including jellyfish and corals, characterized by radial symmetry, diploblasty, and a gastrovascular cavity with an incomplete gut.

Polyp

A cnidarian body type that is usually sessile and living on the bottom, featuring a mouth/anus facing upward.

Medusa

A cnidarian body type that is usually mobile and swimming, featuring a mouth/anus facing downward.

Mesoglea

A layer of gel located between the epidermis and gastrodermis in cnidarians.

Cnidocytes

Specialized cells in cnidarians used for prey capture, containing organelles called cnidae.

Nematocyst

The most common kind of cnida, which features a coiled thread that pops out to stab prey and deposit toxins.

Medusozoans

A major clade of cnidarians that have a medusa in their life cycle, including hydrozoans, scyphozoans (true jellies), and cubozoans (box jellies).

Anthozoans

Cnidarians that have only a polyp stage in their life cycle, such as sea anemones, sea pens, and corals.

Ctenophora

The phylum of comb jellies, featuring approximately $100$ species that are all marine, diploblastic, and have a complete gut with a mouth and separate anus.

Ctenes

Massive, fused cilia arranged in $8$ rows (comb rows) that ctenophores use for swimming.

Bilateria

A clade of animals that are bilaterally symmetrical and triploblastic, with a common ancestor dating back approximately $670$ million years ago.

Lophotrochozoa

A large clade of bilaterians containing approximately $18$ phyla, mostly identified by molecular data and often possessing a trochophore larva or a lophophore.

Trochophore

A tiny, planktonic larval stage found in some lophotrochozoans, such as molluscs and annelids, featuring a band of cilia for locomotion and feeding.

Lophophore

A ring of ciliated, hollow tentacles used for feeding and gas exchange in some lophotrochozoans like ectoprocts and brachiopods.

Platyhelminthes

The phylum of flatworms, containing $20,000$ species that are acoelomate and unitary, characterized by a high surface-area-to-volume ratio to allow for gas exchange via diffusion.

Scolex

The anterior end of a tapeworm, equipped with spines and suckers used to attach to the host's gut.

Proglottids

Sac-like body segments of a tapeworm that contain both ovaries and testes.

Syndermata

A phylum of approximately $2900$ species, mostly rotifers, which are tiny, unitary, and pseudocoelomate.

Corona

A ring of cilia at the anterior end of rotifers used for swimming and feeding.

Mastax

The muscular pharynx of a rotifer that contains jaws for chewing food.

Parthenogenesis

A form of asexual reproduction where females produce diploid eggs that develop without fertilization.

Mollusca

A diverse phylum of $100,000$ species, all unitary and coelomate, possessing three body regions: foot, visceral mass, and mantle.

Radula

A ribbon of teeth found in most molluscs used to scrape material from surfaces for feeding.

Ziconotide (Prialt)

A synthetic form of a conotoxin from cone snails that blocks pain by binding to ion channels, estimated to be $100$ to $1000$ times more effective than morphine.

Annelida

A phylum of $16,500$ species of segmented animals, all unitary and coelomate, possessing a complete gut and a trochophore larva.

Parapodia

Pairs of segmental 'feet' found in errantian annelids that function in movement and gas exchange.

Clitellum

A reproductive structure found in sedentarian annelids, such as earthworms and leeches.