Symmetry in biology Most radially symmetric animals are symmetrical about an axis extending from the center of the oral surface, which contains the mouth to the center of the opposite, , end. Radial symmetry is especially suitable for sessile animals such as the sea anemone, floating animals such as jellyfish, and slow moving organisms such as starfish. Animals in the phyla Cnidaria and Echinodermata are radially symmetric, although many sea anemones and some corals have bilateral symmetry defined by a single structure, the siphonoglyph. Many flowers are radially symmetric or actinomorphic. Roughly identical flower parts – petals, sepals, and stamens – occur at
Venom Other insects, such as true bugs and many ants, also produce venom. At least one ant species ("Polyrhachis dives") has been shown to use venom topically for the sterilisation of pathogens. There are venomous invertebrates in several phyla, including jellyfish such as the dangerous box jellyfish and sea anemones among the Cnidaria, sea urchins among the Echinodermata, and cone snails and cephalopods including octopuses among the Molluscs. Venom is found in some 200 cartilaginous fishes, including stingrays, sharks, and chimaeras; the catfishes (about 1000 venomous species); and 11 clades of spiny-rayed fishes (Acanthomorpha), containing the scorpionfishes (over 300 species), stonefishes