Eventually, I replaced it with a full-size tire, but I've always wondered why manufacturers say you shouldn't use the spare for longer than necessary. Since the spare tire is used so infrequently, carmakers have switched to narrow, compact spares to save space and weight. Of course, a spare tire is a lifesaver when regular tires go pop, but leaving the temporary tire on for longer than the manufacturer recommends invites a host of problems. First, a temporary spare isn't as durable as a normal tire.
Cells have become specialized and form true tissues and cnidarians are the first group to have B nerve cells organized into a nerve net B sense organs (statocysts and ocelli) B extracellular digestion Cnidarian Body Plan The diploblastic cnidarians are radially or biradially symmetrical with oral and aboral ends.
Cnidaria. Cnidaria is a phylum of animals, which contains amazingly beautiful coral reefs, electrifying jellyfish, and many other interesting oceanic creatures. There are about 10,000 species of cnidarians and all of them are unique among all other organisms for the presence of the Cnidocytes. Cnidaria and porifera are two different phyla. â¢ Cnidarians have Cnidocytes but not the poriferans. â¢ Cnidarians have well-organized organ systems but not the poriferans; on the other hand, poriferans have an efficient tunnel system made up of pores but not the cnidarians.