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.
Each cnidae is located within a specialized cell that houses it, this cell is a capsule with an attached hollow thread. Nematocyst is the more familiar term applied to specialized cnidae that are characteristic of scyphozoan and other types of jellies, and other cnidarians. As to the functions: stinging nematocysts function primarily for the capture of prey, and secondarily as a defense mechanism. There are many types of nematocysts, such as those that function to inject toxins to immobilize prey, and those which serve to entangle and hold onto the intended meal by wrapping around it.