BIOL 1108 Lecture Notes - Lecture 39: Symmetry In Biology, Phoronid, Lophotrochozoa
Document Summary
Cell fate is set in early embryo development. Mouth pore forms first in the gastrula. Cell fate is set much later in the blastula (stem cells) Anal pore opens first in the gastrula. Have bilateral symmetry and complex organs that develop from a triploblastic embryo. This anatomical complexity makes possible types of locomotion, feeding, gas exchange, behavior, and reproduction that are unknown in earlier branching groups. Eggs or tapeworm segments in feces are passed into the environment. Eggs or segments are ingested by pigs or humans. Tapeworm embryos hatch, penetrate the intestinal wall, and circular to musculature in pigs or humans. Embryos develop into larvae in muscles of pigs or humans. Humans acquire the infection by ingesting raw or undercooked meat from an infected animal host. Cysts may develop in any organ and are most common in subcutaneous tissue as well as in the brain and eyes. The tapeworm attaches itself to the intestine via hooks on the scolex.
