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biol 1020

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BIOL 1020
Andreas Heyland

Lecture 25 Evolution of Animal Diversity What is an animal?  Animals are • eukaryotic, • multicellular _______________________, and • have cells that lack cell walls.  Animals also use _______________, the eating of food.  _____________________absorb nutrients after digesting food outside their body. © 2012 Pearson Education, Inc. • _________________________is much larger than vertebrate diversity • The large majority of phyla are invertebrates • All vertebrates are chordates … but not all chordates are vertebrates • _________________________________________ Animal diversification began more than half a billion years ago  The oldest generally accepted animal fossils that have been found are __________________________years old.  Animal diversification appears to have accelerated rapidly from then, during the Cambrian period, known as the ___________________________________.  The most celebrated source of Cambrian fossils is the Burgess Shale containing a cornucopia of perfectly preserved animal fossils. © 2012 Pearson Education, Inc. Figure 18.2B_1 Animals can be characterized by basic features of their “body plan”  Animal body plans vary in • ___________________________________, • ___________________________________, • number of ________________________________________, • presence of a ___________________________, and • details of their ___________________________________. © 2012 Pearson Education, Inc. What is an animal?  After the gastrula stage, many animals develop __________________________ into adults.  Other animals, such as the sea star, develop into one or more ______________________________. • A larva is an ___________________________ individual that looks different from the adult animal. • A larva undergoes a major change in body form, called ____________________________ , and becomes a reproductively mature adult.  In vertebrates and insects metamorphosis is regulated by hormones – __________________________ © 2012 Pearson Education, Inc. Figure 18.3A Animals can be characterized by basic features of their “body plan”  Symmetry • Animals that have ____________________have a top and bottom but lack back and front or right and left sides. An imaginary slice through the central axis divides them into mirror images. • Animals with ________________________________have mirror- image right and left sides and a – distinct head, or anterior end, – tail, orposterior end, – back, or dorsal, surface, and – bottom, or ventral, surface. © 2012 Pearson Education, Inc. Animals can be characterized by basic features of their “body plan”  Animals with three embryonic layers may have a ______________________________, a fluid-filled space between the digestive tract and outer body wall that • cushions internal organs and that • enables them to grow and move independently of the body wall. • In soft-bodied animals, fluid in the body cavity forms a ___________________________________. • A _____________________________is completely lined by tissues derived from mesoderm. • A _____________________________is a body cavity that is not completely lined by tissues derived from mesoderm. © 2012 Pearson Education, Inc. Animals with and without • ________________: no coeloms coelomic cavity • __________________: Coelom lined by mesoderm only on the body wall, not around the gut. • __________________
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