ANSC 420 Lecture Notes - Lecture 4: Tight Junction, Blastula, Gastrulation
9 Feb 2013
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Document Summary
The word animal comes from the latin word animalis, meaning havingbreath. In everyday colloquial usage, the word often refers to non-human members of kingdom animalia. Sometimes, only closer relatives of humans such as mammals and other vertebrates are meant in colloquial use. The biological definition of the word refers to all members of the kingdom animalia, encompassing creatures as diverse as sponges, jellyfish, insects and humans. Animals have several characteristics that set them apart from other living things. Animals are eukaryotic and multicellular, which separates them frombacteria and most protists. They are heterotrophic, generally digesting food in an internal chamber, which separates them from plants and algae. They are also distinguished from plants, algae, and fungi by lacking rigid cell walls. All animals are motile, if only at certain life stages. In most animals, embryospass through a blastula stage, which is a characteristic exclusive to animals.
