3.9: How to be an animal
More organized, bigger animal has multiple needs, and therefore, multiple tissues and organs (Fig. 3.9.2):
- locomotion : appendages, skin-muscular bag (A), fins;
- 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”.