Lecture 23 Vocabulary (BIOL211)

This set of vocabulary flashcards covers biological terms related to non-bilaterian and lophotrochozoan animal clades, including anatomical structures, reproductive strategies, and representative species discussed in the BIOL 696B lecture.

Porifera

A phylum comprising approximately $5500$ species of sponges, which are simple, often asymmetric animals that lack true tissues, nerves, muscles, and a digestive system.

Choanocytes

An inner layer of flagellated cells in sponges that resemble choanoflagellates; their flagellae pull water through pores to capture and phagocytose food particles.

Mesohyl

A layer of gelatinous extracellular material located between the two cell layers of a sponge, containing spicules and spongin fibers.

Spicules

Tiny mineralized skeletal structures in sponges made of silicon dioxide or calcium carbonate that provide structural support and 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.

Harp Sponge

A carnivorous species of sponge described in $2010$ from deep water off Monterey that lacks choanocytes and captures prey using hooked, velcro-like spicules.

Eumetazoa

A clade of animals characterized by having true tissues and either radial or bilateral symmetry.

Cnidaria

A phylum of approximately $10,000$ species, including jellyfish and corals, featuring radial symmetry, diploblastic development, and an incomplete gut.

Polyp

The body type of a cnidarian that is usually sessile and lives on the bottom.

Medusa

The body type of a cnidarian that is usually mobile and swims in the water.

Mesoglea

The layer of gel situated between the epidermis (from ectoderm) and the gastrodermis (from endoderm) in cnidarians.

Cnidocytes

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

Nematocyst

The most common type of cnida, which pops out to stab prey and typically deposits toxins.

Planula

The larval stage of a cnidarian that swims in the water before metamorphosing into a juvenile.

Medusozoans

A major clade of cnidarians that includes species with a medusa stage in their life cycle, such as hydrozoans, scyphozoans, and cubozoans.

Cubozoans

Known as "box jellies," these medusozoans have a dominant medusa stage and possess very toxic nematocyst venom.

Anthozoans

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

Coral Bleaching

The expulsion of symbiotic dinoflagellates from coral gastrodermal cells due to warming or other stresses.

Ctenophora

A phylum of approximately $100$ species known as comb jellies, which are marine, diploblastic, radially symmetrical, and possess a complete gut.

Ctenes

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

Bilateria

A clade of animals characterized by bilateral symmetry, triploblastic development, and typically a complete gut with both a mouth and an anus.

Lophotrochozoa

A large clade of bilaterians identified by molecular data, many of which feature either a trochophore larva or a lophophore.

Trochophore

A tiny, planktonic larval stage found in some lophotrochozoans, such as molluscs and annelids, characterized by a band of cilia.

Lophophore

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

Platyhelminthes

Flatworms; a phylum of approximately $20,000$ species that are acoelomate, unitary, and have high surface-area-to-volume ratios due to their flattened bodies.

Trematodes

Internal parasites of vertebrates with complex life cycles involving two larval stages and often a snail as an intermediate host.

Schistosoma

The genus of trematode that causes schistosomiasis, a disease infecting approximately $200$ million people worldwide and damaging the liver, spleen, and other organs.

Tapeworms

Parasitic flatworms that lack a mouth and gastrovascular cavity, instead absorbing food directly across their body wall from the host's gut.

Scolex

The head-like anterior part of a tapeworm featuring spines and suckers for attachment to the host.

Proglottids

The segments making up the body of a tapeworm, each containing ovaries and testes.

Syndermata

A group comprising approximately $2900$ species, mostly rotifers, which are tiny, unitary, and pseudocoelomate.

Corona

A ring of cilia at the anterior end of a rotifer used for locomotion and suspension feeding.

Mastax

A specialized structure in rotifers containing jaws used for chewing food.

Cryptobiosis

An inactive state entered by rotifers during dry conditions where metabolism stops almost completely for decades.

Cyclical Parthenogenesis

A reproductive strategy in rotifers involving asexual reproduction (females making diploid eggs) during good conditions and sexual reproduction during harsh conditions.

Bdelloid Rotifers

A group of rotifers that are all female and have reproduced exclusively via parthenogenesis for at least $80$ million years.

Ectoprocts

Colonial, coelomate lophotrochozoans that use a lophophore for feeding and live in mineralized skeletal boxes connected by blood vessels.

Brachiopods

Unitary, coelomate lophotrochozoans with two shells made of calcium carbonate or calcium phosphate that resemble clams.

Molluscs

A phylum of approximately $100,000$ species characterized by a three-part body plan: a foot, a visceral mass, and a mantle.

Mantle

In molluscs, a sheet of tissue covering the dorsal surface that secretes the shell and houses the mantle cavity.

Radula

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

Conotoxins

Polypeptides comprising $10-30$ amino acids produced by cone snails to paralyze prey by binding to ion channel proteins.

Ziconotide

A synthetic form of $\omega$-conotoxin MVIIA, marketed as Prialt, which is used as a non-addictive pain blocker with $100-1000$ times the effect of morphine.

Chitons

Marine molluscs with eight overlapping shell plates on their dorsal surface and iron oxide in their radular teeth.

Gastropods

A group of molluscs including snails and slugs that typically have one shell or none and move using a single muscular foot.

Bivalves

Aquatic molluscs with two shells and no radula, such as clams and mussels, that typically feed via suspension feeding using large gills.

Cephalopods

Active marine predators like squid and octopus that move by jet propulsion and have modified their foot into arms, tentacles, and a siphon.

Annelids

A phylum of approximately $16,500$ species of segmented animals that use coelomic cavities as a hydrostatic skeleton.

Errantians

A clade of mostly marine annelids that move using pairs of parapodia containing chitinous bristles called chaetae.

Sedentarians

A clade of annelids, including earthworms and leeches, that generally have reduced or no parapodia and chaetae.

Clitellum

A reproductive structure found in sedentarian annelids like earthworms and leeches.