Animals Chapter 25

Common Characteristics of all animals: Multicellular Eukaryotes Have membranes around organelles No cell walls or chloroplasts Get food by feeding on other animals Heterotrophs Move based on the way they obtain food Sessile-animals that don’t move (ex. Sea Urchin) Digest food 3 steps of digestion: Break down food Use food for energy Store excess food as glucose/glycogen

Development overview: All animals have the same development process Zygote cleavage (splitting of the cell)

Gastrula formation

Layers of gastrula (germ layers) Ectoderm- (outside layer) Forms skin, nerves, smaller vessels Mesoderm-(middle layer) Forms muscles, Large Blood vessels, reproductive organs Endoderm- (innermost layer) Forms digestive tract and organs

Animal development cont… Protostome- opening in the indented space becomes a mouth (lower organisms) Deutorostome-opening in the indented space becomes on anus and the mouth forms from cells elsewhere (higher animals like mammals)

Coelom- body cavity completely surrounded by a mesoderm/lining Ex. Human, higher organisms

types of body cavities Acoelomate (no coelem) Pseudocoelomate- Has all the layers of development but no cavity for organs Has 1 opening to body Pseudocoelomate- has all 3 layers of development, a digestive tract and fluid filled cavity (coelem) for organs Has 2 body openings Coelomate- has the 3 layers and a digestive tract and fluid filled cavity (coelem) *also has a membrane attached to the organs

3 symmetries of animals:

Symmetry of animals: Symmetry- balance of an animals body proportions 3 kinds of symmetry: 1. asymmetry (no balance)- Body is irregular shaped Cannot cut it anywhere and make the halves balance Includes sessile organisms (don’t move)

Symmetry types cont… 2. radial symmetry- body can be divided into equal halves by cutting at multiple locations (ex. Hydra) 3. bilateral symmetry- can cut the body into equal halves at 1 location The halves are mirror images These organisms move very efficiently Ex. Man, mammals, birds

Animal protection and support: skeleton- protects and supports 2 kinds of skeletons in animals: Exoskeleton- on the outside of body Hard waxy covering In insects, the skeleton is made of chitin Molting-shedding of exoskeleton Endoskeleton- skeleton within-supports body and protects organs

Animal protection and support cont… There are 2 types of organism groups based on if they have a backbone 1.Vertebrates- have a backbone 2. Invertebrates- no backbone If an animal has an exoskeleton, it cannot have backbone

Body direction terms: Dorsal-toward the back Ventral-toward the stomach

Body terms cont… Posterior-toward the tail/back Superior-above Inferior-below Anterior-toward the front