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Ch 25 What Is An Animal 25.1. Typical Animal Characteristics A. Characteristics of Animals – Eukaryotic, multicellular, _________________, heterotrophic organisms 1. Methods for obtaining food vary – mobile animals have the ability to seek found whereas sessile animals rely on food coming to them (ex: water brings food to barnacles) a. _________________ – organisms that don’t move from place to place 2. Animals must digest food - animals are _________________ and must digest food. Most animals have a _________and ___________, some only have __________body opening. 3. Animal cell adaptations – animals have specialized _______________to carry out metabolic functions B. Development of Animals – most animals develop from a single, fertilized egg called a zygote. 1. _________________ –occurs when sperm fertilizes an egg. It may be internal or external 2. Cell division – zygote divides by mitosis a. _________________ – a hollow ball of cells 3. Gastrulation - blastula folds inward a. _________________ – a structure made of two layer of cells with an opening at one end b. _________________ - the layer of cells on the outer surface of the gastrula c. _________________ – the layer of cells lining the inner surface 4. Formation of the mesoderm – found in the middle layer of the embryo a. _________________ - the third cell layer found in the developing embryo between the ectoderm and the endoderm b. protostome - an animal with a _________ that develops from the opening in the gastrula (ex: earthworms/insects) c. _________________ – an animal in which the mouth develops from cells elsewhere on the blastula (ex: fish, birds and humans) 5. Continued growth and development – In some animals, the _________________ develops into a _________________ which is different from the adult version. (ex: echinoderms and insects) 6. Forming an adult animal – eventually, all juveniles reach sexual maturity and the life cycle can repeat 25.2. Body Plans and Adaptations A. What is Symmetry? a. _________________ – a balance in proportions of an object or organism 1. _________________ in a sponge – an animal with an irregular shaped body (ex: sponge) 2. Radial symmetry in a hydra a. _________________ _________________ – can be divided along any plane through a central axis into roughly equal halfs 3. Bilateral symmetry – ex: any organism with a head a. _________________ _________________ – can be divided down its length into similar right and left halves that form mirror images. d. ______________ – back surface b. _________________ – head end c. ____________ – tail end e. _________________ – belly surface B. Bilateral Symmetry and Body Plans 1. Acoelomate flatworms have no body cavities – “A” = without, “coelom” = body cavity a. _________________ – 3 cell layers – ectoderm, endoderm, mesoderm - but no body cavity 2. Pseudocoelomates have a body cavity – “pseudo” = false. Body cavity develops between the endoderm and the mesoderm a. _________________ – a fluid-filled body cavity partly lined with mesoderm 3. The coelom provides space for internal organs a. _________________ – a fluid-filled space that is completely surrounded by mesoderm C. Animal Protection and Support a. _________________ – a hard, waxy covering on the outside of the body that provides a framework for support b. _________________ – an internal skeleton that provides support inside an animal’s body c. _________________ – an animal that does not have a backbone d. _________________ – an animal with a backbone