• Animals are multicellular beings with a variety of tissue types.
• All animals can eat their food and digest it inside their bodies.
• All animals make collagen as a structural protein to maintain their cells together.
• All animals produce embryos. The way the embryo develops will decide and complexity of the adult.
• The most primitive animals, like sponges and jellyfish, only have one hole that serves as both mouth and anus, while more modern species develop both a mouth and anus.
• Many animals show bilateral symmetry, with two halves that look the same. Others show radial symmetry, with a more circular shape divided in equal parts.
• Many animals pass by one or several larval states, having many transformations before becoming an adult. The most well-known example is the change from a caterpillar onto a butterfly.

Sea Sponge; photo by Dimsis cc-by	Comb Jelly; photo by NOAA cc-by	Velvet Worm; photo by Ggalice cc-by

Sources:

-The Tree of Life - www.tolweb.org:
-The Variety of Life, Colin Tudge, 2000

Citation: García, A.I. 2015. The Tree Of Nature (Online) at http://thetreeofnature.com

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