The body wall of cnidarians consists of an outer layer or epidermis, an inner layer or gastrodermis, and a middle layer or mesoglea. Cnidarians lack organs and posses a primitive nervous system known as a neural net. Cnidarians exhibit two basic structural forms, a medusa and a polyp. The medusa form is a free-swimming structure which consists of an umbrella-shaped body (called a bell), a fringe of tentacles that hang from the edge of the bell, a mouth opening located on the underside of the bell, and a gastrovascular cavity.
Tropic of Capricorn, parallel of latitude at 23Â°30â south of the equator; it is the southern boundary of the tropics.This parallel marks the farthest point south at which the sun can be seen directly overhead at noon; south of the parallel the sun appears less than 90Â° from the northern horizon at any day of the year.ropic of Capricorn, parallel of latitude at 23Â°30â south of the equator; it is the southern boundary of the tropics.
In the Northern Hemisphere, it occurs when the sun is directly over the Tropic of Capricorn, which is located at 23.5Â° south of the equator and runs through Australia, Chile, southern Brazil, and northern South Africa. This year, the Northern Hemisphere winter solstice will occur at 4:03 pm MST on December 21, 2014.For a complete listing of the dates of the winter and summer solstice's and spring and fall equinox's through 2020, check out this site from the U.S. Naval Observatory.he summer solstice occurs when the sun is directly over the Tropic of Cancer, which is located at 23.5Â° North, and runs through Mexico, the Bahamas, Egypt, Saudi Arabia, India, and southern China. Because of the Earth's tilt, the sun is directly over the Tropic of Cancer near June 21.