Marine Invertebrate Zoology Practice Flashcards

A comprehensive set of vocabulary flashcards derived from lecture notes on lophotrochozoan phyla, including Annelida, Platyhelminthes, Rotifera, and Nemertea, as well as the Phylum Cnidaria.

Phylum Annelida

Segmented worms that are bilaterally symmetrical and possess three tissue layers: endodermis (gastrodermis), mesodermis, and ectodermis (epidermis).

Metamerism

Segments of the entire body cross-section.

Homonymous

A condition where segments of the body are mostly similar.

Tagmata

The body region in a segmented animal, such as the head, thorax, or abdomen.

Prostomium

The dorsal-most part of the head in polychaetes containing many sensory organs like eyes, tentacles, and palps.

Peristomium

The segment of the polychaete head that contains the mouth.

Parapodia

Fleshy, lateral appendages in polychaetes used for locomotion, comprised of a dorsal notopodium and a ventral neuropodium.

Plesiomorphy

A primitive or ancestral character directly derived from the original condition with no change.

Apomorphy

A derived character that differs from the original condition via evolution.

Homoplasy

An analogous structure that looks like an ancestral trait but evolved independently.

Podocyte

A specialized cell in the metanephridia that produces primary urine from blood by providing pressure to run the system.

Nuchal organs

Ciliated pits in polychaetes that are believed to be chemosensory.

Statocysts

Gravity-sensing organs found in some polychaetes.

Epitoke

The sexual stage of a polychaete, often dioecious, which may reproduce by rupture.

Trochophore

The planktonic larval stage of many polychaetes characterized by the presence of cilia.

Planktotrophic

A larval development strategy where the organism uses plankton for energy.

Lecithotrophic

A larval development strategy where the organism uses yolk for energy.

Seston

A combination of plankton plus non-living suspended matter such as mucus, fecal matter, and exoskeletons.

Marine Snow

Congregated seston and mucus colonized by bacteria that serves as the primary source of energy for the deep sea.

Nekton

Fast-swimming animals that can swim faster than lateral currents.

Phylum Platyhelminthes

Flatworms that are bilaterally symmetrical, acoelomate, and possess a multi-lobed digestive tract with no anus.

Protonephridia

Excretory organs used for osmoregulation that utilize a mechanical filter and cilia to create negative pressure.

Chromatophores

Pigment cells that can change color quickly by using microtubules and kinesin to move melanin granules.

Rhynchocoel

A fluid-filled cavity in Phylum Nemertea that houses the eversible proboscis.

Phylum Rotifera

Mostly microscopic pseudocoelomate animals with a ciliated corona for feeding and swimming.

Mastax

A muscular pharynx in rotifers used for lapping food.

Cryptobiosis

A state of suspended cellular activity that allows an organism to withstand harsh environmental conditions.

Anhydrobiosis

A form of cryptobiosis involving the reduction of cellular water and protection of the cell cytoskeleton.

Cnidocyte

Unique stinging cells in Phylum Cnidaria that contain organelles called nematocysts.

Nematocyst

A venomous organelle triggered by osmotic pressure and mechanical stimulation ($Cnidocil$) to penetrate and deliver toxins to prey.

Mesoglea

A non-cellular, jellylike layer between the epidermis and gastrodermis that manipulates ions for buoyancy and stores energy for movement.

Zooxanthellae

Marine dinoflagellate endosymbionts that live in the tissues of corals and providing food in the form of simple sugars and amino acids.

Planula

A ciliated, non-feeding larval stage found in many Cnidarians.

Scyphistoma

The solitary, non-sexual polyp stage of the Class Scyphozoa.

Strobilation

The process by which a scyphistoma buds off ephyrae (juvenile medusae).

Ephyra

The juvenile medusa stage of a jellyfish that develops into an adult medusa.