VIEWS: 76 PAGES: 20 POSTED ON: 8/7/2012
Phylum Cnidaria Phylum Cnidaria Cnidarians have special stinging cells called cnidocytes. They have long flexible tentacles and usually live in sea water. Because they have a hollow gut called a__________, they are known as ____________ as well as Cnidarians. Phylum Cnidaria Characteristics of Cnidarians Body plan Two cell layers Specialized structures Nerve net Sexual and asexual reproduction Phylum Cnidaria Body Plan Cnidarians generally have _______ symmetry. Phylum Cnidaria Body Plan Cnidarians live in the ocean and can have one of two different body plans: 1. _______– free swimming 2. ______- sessile Phylum Cnidaria Two Cell Layers Cnidarians are advanced beyond sponges in the development of their cell layers. Although sponges also have two cell layers, in cnidarians the cell layers are organized into ______. These tissues have specific functions and serve specific purposes. Phylum Cnidaria Two Cell Layers A jelly-like substance, the__________, separates the two cell layers. The three together make up a body wall called a _____________cavity that surrounds a central cavity. Phylum Cnidaria Specialized Structures Cnidarians are aggressive hunters for food. They have strong _________ cells which shorten and lengthen to allow _________ of the organism. This movement allows the tentacles to capture food and allows the cnidarian to swim and actively seek prey. Phylum Cnidaria Specialized Structures Cnidarians also have specialized stinging cells called _________. Cnidocytes contain a coiled protein strand called a __________. The strand has poison barbs or spines on it. Phylum Cnidaria Specialized Structures When Cnidarians encounter prey, the cnidocyte fires the nematocyst. The poison on the barb of the nematocyst paralyzes or kills the prey. The Cnidarian then draws the strand back in and hauls the prey in to be digested. Phylum Cnidaria Nerve Net Cnidarians lack a sophisticated nervous system but possess a ________. Nerve nets are considered to be the_______ form of a nervous system. Phylum Cnidaria Nerve Net Nerve impulses cause cell contractions, but no center for control exists with a nerve net. There is _______ or central nervous system in cnidarians. Phylum Cnidaria Sexual and Asexual Reproduction Sexual reproduction in the common jellyfish 1. The adult female medusa (free-swimming form) releases ____ into the water. The adult male medusa releases ______ into the water. Fertilization is _______. Phylum Cnidaria Sexual and Asexual Reproduction 2. Fertilization results in formation of a ________. This stage is sometimes called the larva or _______. The planula is free- swimming due to the presence of cilia. Phylum Cnidaria Sexual and Asexual Reproduction 3. The planula settles to the ocean floor or any sturdy surface and develops into a sessile stage called the ________. 4. The polyp matures by developing a ________ and __________. As it grows, layers of __________ form inside the ring of tentacles. Phylum Cnidaria Sexual and Asexual Reproduction 5. Medusa _______ and swim off in the water to mature and release more eggs and sperm. Phylum Cnidaria Sexual and Asexual Reproduction Asexual Reproduction in Cnidarians Asexual reproduction is usually by _______. Hydra reproduce in this manner. Small buds are formed on the exterior of their body. The buds grow, mature within a few _____, and fall off the adult form. They then begin life as independent new individuals. Phylum Cnidaria Classes of Cnidarians 1. Class Hydrozoa These include the _____ and the obelia. Phylum Cnidaria Classes of Cnidarians 2. Class Scyphozoa This class is composed of ________. The _______ is the dominant body form. Phylum Cnidaria Classes of Cnidarians 3. Class Anthozoa ____________ and _______ compose Class Anthozoa. The _______ is the only body form present. Polyps grow as solitary individuals or in colonies.
Pages to are hidden for
"Phylum Cnidaria - Get Now PowerPoint"Please download to view full document