LESSON 8: PHYLUM CNIDARIA

alternatively referred to as coelenterates; their distinguishing feature is cnidocytes, specialized cells present on the tentacles that is used for capturing prey and defense

found in organisms which show morphological features, internal or external, of both bilateral and radial symmetry

cup-like in appearance; composed a cylindrical body known as the column, and a mouth surrounded by food-gathering tentacles facing upwards; a much primitive form of cnidarians that lack sensory organs; seen in sea anemone, hydra, and corals

umbrella-like in appearance; more developed form of cnidarians; seen in jellyfishes

functions in digestion, the exchange of respiratory gases and metabolic wastes, and the discharge of gametes; presence of a body wall which encloses a cavity

tentacles that have specialized stinging cells, which have nematocysts used to capture prey, ward off enemies, or anchorage

outer layer of the body wall

inner layer of the body wall

sometimes referred to as the mesohyll; gelatinous substance between the epidermis and the gastrodermis; mostly composed of water, it also includes fibrous proteins like collagen, as well as muscle bundles and nerve fibers

also known as cnidocytes or cnidoblast;

long tube armed with spines that can deliver paralyzing toxins and immunological reactions in the envenomated organism; the venom contains enzymes, potent pore forming toxins, and neurotoxins

also referred to as the class of hydra; acknowledged as the most diverse group of cnidarians

commonly known as to as the class of true jellyfishes; medusa form dominates the life cycle; characterized by the presence of short or long tentacles with nematocysts; have a ring of muscles that lines the dome of their bodies; these structures provide them with the contractile force they need to swim through water

alternatively recognized as to as the class of box jellyfishes; can produce an extremely potent venom

also known as to as the class of sea anemones and corals; mouth surrounded by tentacles with nematocysts; commonly polyps and have limited locomotion