Exercise 3: Phylum Porifera and Phylum Cnidaria Vocabulary

Vocabulary practice flashcards covering anatomical features, cellular characteristics, reproductive methods, body forms, and classifications of Phylum Porifera and Phylum Cnidaria.

Phylum Porifera

The simplest pore-bearing multicellular invertebrates that operate at the cellular level with no true tissues, organs, or body systems, displaying radial symmetry or asymmetry.

Choanocyte

The defining cell type of Phylum Porifera that uses a flagellum to generate water currents and filter food particles from the water.

Osculum

The large opening at the top of a sponge where water exits after passing through the spongocoel.

Ostia

The small pores on the outer sides of a sponge body that allow water to flow into the internal spongocoel.

Spongocoel

The large central cavity of a sponge lined with choanocytes and other specialized cells.

Spongin

A collagen- and keratin-like structural protein that forms the flexible, microporous skeletal matrix in most marine demosponges.

Crystalline Spicules

Rigid, needle-like mineral structures made of calcium carbonate ($CaCO_3$) or silica ($SiO_2$) that provide structural support and protection to sponges.

Ascon

The simplest canal system body form in sponges, where water enters through ostia directly into a single central spongocoel.

Sycon

A sponge body canal system characterized by folded walls containing radial channels lined with choanocytes.

Leucon

The most complex and common sponge body canal system, featuring an extensively branched system of canals and rounded flagellated chambers.

Class Calcarea

A class of marine sponges characterized by spicules composed entirely of calcium carbonate ($CaCO_3$), represented by species such as Guancha lacunosa.

Class Hexactinellida

A class of marine sponges, commonly known as glass sponges, characterized by six-rayed siliceous spicules and a delicate, colorless structure, such as Euplectella (Venus flower basket).

Class Demospongiae

The largest class of sponges comprising about 90% of all living sponge species, possessing skeletons composed of siliceous spicules, spongin, or both.

Class Sclerospongiae

Coralline sponges characterized by dense, multilayered calcium carbonate skeletons organized in chronological concentric bands similar to reef corals.

Gemmule

An dormant, asexual reproductive capsule formed by sponges to survive unfavorable environmental conditions.

Phylum Cnidaria

A phylum of aquatic invertebrates displaying radial or biradial symmetry, characterized by specialized stinging cells called cnidocytes and two distinct body plans (polyp and medusa).

Cnidocyte

The defining specialized cell type in cnidarians containing a stinging organelle used for prey capture and defense against predators.

Nematocyst

A coiled, tubular, harpoon-like organelle within a cnidocyte that discharges upon chemical or mechanical stimulus to inject venom into prey.

Polyp

A sessile body plan in cnidarians shaped like a hollow cylinder or bag attached to a hard surface with the mouth and tentacles facing upward.

Medusa

A free-swimming, umbrella- or bell-shaped body plan in cnidarians with the mouth and tentacles hanging downward.

Gastrovascular Cavity

The primary internal body cavity in cnidarians that serves both digestive and circulatory functions, enabling gas exchange via diffusion.

Class Hydrozoa

A class of marine and freshwater cnidarians that typically alternate between polyp and medusa body forms, often displaying colonial polymorphism (e.g., Hydra, Obelia).

Hydranth

The terminal oral end of a hydrozoan polyp that bears the mouth and surrounding tentacles.

Hypostome

The conical elevation located around the mouth region on the oral end of a Hydra.

Basal Disc

The aboral foot region of a Hydra used for attachment to a substrate.

Pneumatophore

A specialized, gas-filled float polyp found in polymorphic colonial hydrozoans such as the Portuguese man o' war.

Gastrozooid

A specialized feeding polyp in a polymorphic cnidarian colony.

Gonozooid

A specialized reproductive polyp in a polymorphic cnidarian colony responsible for producing medusae.

Dactylozooid

A specialized defensive and prey-capturing polyp ('fishing tentacle') in polymorphic cnidarian colonies that is heavily armed with cnidocytes.

Class Scyphozoa

A class of exclusively marine cnidarians known as 'true jellyfish' that possess a bell-shaped morphology and a dominant free-swimming medusa stage.

Class Cubozoa

A class of solitary, box-shaped marine jellyfish with muscular pads called pedalia, containing some of the most venomous cnidarians.

Pedalia

Muscular pad-like projections at the corners of the bell margin in box jellyfish (Class Cubozoa) from which tentacles arise.

Class Anthozoa

A class of exclusively marine cnidarians known as 'flower-animals' that exist solely as sessile polyps with no medusa stage (e.g., corals and sea anemones).

Corallite

The skeletal cup structure secreted and inhabited by an individual coral polyp.