Hobbies And Interests
Sponges
Probably the only asymmetrical creature people are familiar with are sponges. These organisms are multi-cellular, like humans; however, they come in a large variety of forms. Their sizes vary as well; some can be several feet wide, while others only grow to a few inches. These animals attach to rocks and absorb algae, as well as bacteria--although they lack nervous and circulatory systems. Sponges exist in marine water all around the world and reproduce through both asexual and sexual reproduction, depending upon their habitat.
Placozoans
Another type of marine animal that develops asymmetrically are placozoans. These marine creatures are extremely small and transparent. Less than a quarter of an inch in diameter, these creatures have two different asymmetrical sides. Placozoans only contain gland cells, cover cells and mesenchyme cells, as well as flagella--all of which total only a couple of thousand cells. Only two types of species exist and, like sponges, placozoans reproduce both sexually and asexually.
Radial Symmetry
Often confused with asymmetry is radial symmetry. Instead of having completely random shapes and sizes throughout the organism, radial symmetry organizes the shape and size around a central axis point, much like the symmetry of a circular pie. Several marine animals display this type of symmetry, most notably animals such as jellyfish or coral. Radial animals are often immobile creatures for much of their lifespan.
Confusion with Plants
One of the first things people will notice about asymmetrical animals is that they look very similar to exotic plants. Although on the surface they may look like plants, underneath the surface, cells differ. Asymmetrical animals--like radial and bilateral symmetric animals--have eukaryotic cells; plants on the other hand, have prokaryotic cells.