Cnidaria and Protostomes: Lophotrochozoans and Nematodes

Flashcards covering key vocabulary terms and definitions from the lecture on Cnidaria, Protostomes (Lophotrochozoans including Platyhelminthes, Annelida, Mollusca, Cephalopods), and Nematoda (Roundworms).

Cnidaria

Commonly known as "nettle animals," a group including corals, jellyfish, sea anemones, hydrozoans, and siphonophores.

Polyp (Cnidaria)

The sedentary (sessile, non-moving) body form in the cnidarian life cycle.

Medusa (Cnidaria)

The mobile body form in the cnidarian life cycle.

Nematocyst

An organelle in cnidarians that functions like a mini-harpoon, used for capturing prey, defense against predators, and defending territory, releasing toxins upon piercing.

Coral

A polyp form cnidarian that lives in large colonies and secretes calcium carbonate (CaCO3) to build its body, contributing to coral reefs.

Coral reefs

Millions of coral skeletons with living corals on their edges, providing critical habitat, protecting coastlines, sequestering carbon, fixing nitrogen, filtering water, and providing nutrients.

Dinoflagellates

Autotrophic protists that live inside corals and perform photosynthesis, providing energy to the corals.

Plankton

Organisms that drift in the ocean, moved by tides and currents, classified by size, type, and drifting duration.

Protostomes

A large and diverse group of animals, including lophotrochozoans and ecdysozoans.

Lophotrochozoans

A group within protostomes that grows incrementally by adding to their skeletal elements, as seen in shelled organisms.

Platyhelminthes

The group of animals commonly known as flatworms.

Acoelomate

An organism that possesses no body cavity (coelom), characteristic of flatworms.

Parasite

An organism that lives on or in another organism (its host) and benefits by deriving its nutrition at the expense of the host.

Human liver fluke

A flatworm parasite with a complex life cycle requiring a human, a snail, and a fish as hosts.

Schistosoma

A flatworm parasite that causes the disease schistosomiasis.

Schistosomiasis

A disease caused by the Schistosoma parasite, prevalent in tropical regions and infecting millions of people yearly.

Definitive host

The host in which a parasite reaches maturity and reproduces sexually.

Intermediate host

Any host that a parasite lives in between its definitive hosts, where it may undergo larval development or asexual reproduction.

Hermaphroditic

Possessing both male and female reproductive organs, allowing for sexual reproduction often with mutual sperm exchange.

Annelida

The group of segmented worms, including earthworms, polychaete worms, and leeches.

Coelom

A hollow, fluid-filled body cavity present in annelids and other animals, acting as a cushion for internal organs and providing structural support.

Leech

A parasitic annelid that feeds on blood, known for producing anticoagulants and anti-inflammatory molecules in its saliva, and has medicinal uses for reattaching severed tissues.

Anticoagulant

A substance, like those produced in leech saliva, that prevents blood clotting.

Mollusca (Mollusks)

A very diverse group of animals including shelled organisms like chitons, snails, and bivalves, and shell-less ones like octopuses.

Blue-ringed octopus

One of the most venomous animals on the planet, a mollusk that carries a potent neuromuscular toxin capable of causing paralysis and death.

Nudibranch

Marine sea slugs that are a type of mollusk, often brightly colored, and known for advertising their defense mechanisms such as toxic secretions or acquired nematocysts.

Mantle (Mollusks)

A sheet of skin in mollusks that in shelled species helps develop the shell by adding layers, contains gills for gas exchange, and in cephalopods, uses a cavity to forcibly eject water for locomotion.

Radula

A hardened, tongue-like structure found in mollusks, primarily used for scraping food off surfaces, but can be modified for manipulating, puncturing, or slicing food.

Cephalopods

A group of mollusks that includes octopuses, cuttlefish, squids, and nautiluses.

Nautilus

A cephalopod unique for its intricate chambers that allow for buoyancy control and the ability to reproduce multiple times in its life cycle.

Giant squid

The largest invertebrate, reaching up to 60 feet long, with eyes the size of volleyballs and tentacles the length of school buses, historically a subject of folklore.

Axons

Parts of a nerve cell (neuron) that carry nerve impulses away from the cell body; notably giant and fast in cephalopods, contributing to their highly developed nervous system.

Chromatophores

Specialized cells in cephalopods that allow them to change color rapidly for disguise, confusion, courtship, and predation.

Nematoda (Roundworms)

A group of worms with a simple 'tube within a tube' body plan; many are free-living decomposers, and many are parasites of plants and animals.

Trichinella

A roundworm parasite of mammals (rodents, pigs, humans) that causes trichinosis; larvae form cysts in muscle tissue.

Trichinosis

A disease caused by the Trichinella parasite, characterized by symptoms like abdominal pain, vomiting, fever, headaches, and aching joints, often associated with consuming undercooked meat.

Insect parasitic nematodes

Nematodes that are used as a form of biological pest control, infecting and killing insects in soil and turf grass.

Ascaris

A parasitic roundworm known for its extremely high reproductive output, producing 100,000 to 200,000 eggs per day.