Key Vocabulary Terms in Cnidarians

Flashcards defining key terms related to Cnidarians to aid in understanding their biology and characteristics.

Cnidarians

A phylum of animals characterized by the presence of cnidocytes, radial symmetry, and two body forms, polyp and medusa.

Hydrozoa

A class within Cnidaria that includes hydras and Obelia, often with both polyp and medusa stages.

Scyphozoa

A class in the Cnidaria phylum known as true jellies, which have a dominant medusa stage.

Anthozoa

A class of Cnidarians that includes sea anemones and corals, which do not have a medusa stage.

Nematocyst

A specialized cell in Cnidarians that contains a stinging structure for capturing prey.

Cnidocyte

A type of cell found in Cnidarians that houses nematocysts.

Mesoglea

The gelatinous substance that separates the epidermis and gastrodermis in Cnidarians.

Polyp

The sessile form of Cnidarians, characterized by a cylindrical body and a mouth surrounded by tentacles.

Medusa

The free-swimming form of Cnidarians, typically bell-shaped and characterized by tentacles hanging down.

Gastrovascular Cavity

A central cavity in Cnidarians that functions in digestion and distribution of nutrients.

Diploblastic

An organism with two primary germ layers: the ectoderm and endoderm, like in Cnidarians.

Radial Symmetry

A body plan in which body parts are arranged around a central axis, as seen in Cnidarians.

Extracellular Digestion

The process of breaking down food outside cells, occurring in the gastrovascular cavity of Cnidarians.

Coral Reefs

Underwater structures made from calcium carbonate secreted by corals, providing habitat for diverse marine life.

Strobilation

A form of asexual reproduction in certain Cnidarians, where the medusa buds off from the polyp.

Planula

The free-swimming larval stage of Cnidarians, typically formed after fertilization.

Amoebocytes

Specialized cells in sponges that can move and perform various functions including digestion and transport of nutrients.

Cnidarian Life Cycle

The life cycle of Cnidarians often involves both sexual (medusa) and asexual (polyp) reproduction stages.

Hydrostatic Skeleton

A structure found in Cnidarians where fluid-filled cavities provide support and shape to the body.

Symbiosis

A mutually beneficial relationship between different organisms, which is common in corals and their symbiotic algae.

Zooxanthellae

Photosynthetic algae that live in the tissues of corals, providing them with energy and color.

Anemonefish

Fish that live in a symbiotic relationship with sea anemones, providing protection and food.

Cnidarian Nervous System

A decentralized nerve net that allows for basic responses to stimuli in Cnidarians.

Chemical Defenses

Substances produced by some Cnidarians that deter predators, such as toxins in some jellyfish.

Epidermis in Cnidarians

The outer layer of cells that covers the body of Cnidarians, providing protection.

Gastrodermis in Cnidarians

The inner layer of cells lining the gastrovascular cavity in Cnidarians, involved in digestion.

Tentacles in Cnidarians

Arms surrounding the mouth of Cnidarians, equipped with cnidocytes for capturing prey.

Benthic Zone

The ecological region at the lowest level of a body of water, including sediment surface and sub-surface layers.

Aquatic Habitat

The natural environment in which aquatic organisms live, characterized by water bodies like oceans, rivers, and lakes.

Reproductive Polyp

A type of polyp in some Cnidarians specialized for reproduction, producing medusae asexually.

Hydra

A genus of small, freshwater Cnidarians belonging to the class Hydrozoa, known for their regenerative abilities.

Sea Pen

A type of colonial Cnidarian that resembles a quill pen, with a soft body and a hard, anchored structure.

Colony Formation

The process by which individual polyps of certain Cnidarians live together and function as a single organism.

Nutrient Absorption

The process by which Cnidarians take up nutrients from their gastrovascular cavity after extracellular