3.9: How to be an animal

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More organized, bigger animal has multiple needs, and therefore, multiple tissues and organs (Fig. 3.9.2):

locomotion: appendages, skin-muscular bag (A), fins;

3.9.01.PNG — Figure 3.9.1 : From blastaea to phagocytella: hypothetical scenario. See explanations of these terms in the text.

3.9.02.PNG — Figure 3.9.2 : “Ideal worm.” See the text for explanation of letters.

support: many types of skeleton (endoskeleton, chitinous exoskeleton, shells, skin plates) and hydrostatic skeleton based on body cavities filled with liquid (A + K + M);
feeding and excretion: mouth, anus, intestines, pharynx (G), stomach (J), digestion glands (like liver, I) etc.;
osmoregulation: simple nephridia (C) and complicated kidneys;
gas exchange: external gills (B), internal lungs and tracheas;
circulation: open (M) or closed blood system with hear(s) (L);
reception: eyes (D), mechanical sensors (ears, hairs), chemical sensors (nose) and many others;
communication: neural cells (neurons), nerves (groups of neurons) (F), ganglia (E) and brain (masses of neurons);
reproduction: sexual organs filled with sexual cells (N), male and female, separately or together, and fertilization “tools”.

3.9.03.png — Figure 3.9.3 : Body of the vertebrate: compare with the worm above.