BIOL 119 Lecture Notes - Lecture 1: Gastrovascular Cavity, Triploblasty, Bilateria
Document Summary
Eukaryotes that share key traits: multicellularity with cells that. Obtain necessary carbon compounds from other organisms. Most ingest their food rather than absorbing it: motility. Move under their own power at some point in their life cycle: all animals except sponges also have. Neurons that transmit electrical signals to other cells. Muscle cells that change the shape of the body by contracting. Animals occur in a clade called opisthokonta: fungi and choanoflagellates also in this clade. Animals are similar to multicellular fungi in that: both are multicellular heterotrophs, both digest and absorb nutrients. But: animals are the only multicellular heterotrophs that ingest before digesting. Comes from three types of data: fossils, comparative morphology, comparative genomics. Oldest fossils more than 600 million years old. Most modern phyla appear around 550 million years ago during the cambrian explosion. Sponges share key characteristics with the choanoflagellate outgroup: both sessile-immobile, both feed similarly: sponge feeding cells, choanocytes, trap and ingest food particles.
