Body Cavity Body cavity- fluid filled space that forms between the digestive tract and the outer wall of the body. Aids in movement and acts as a reservoir and medium of transport for nutrients and wastes.
Animal Kingdom Invertebrates Animals without a Backbone or Spinal Column Vertebrates Animals with a Backbone or Spinal Column: (All these animals are in the phyla Chordata and the subphyla Vertebrata.)
Vertebrates Vertebrates are a subphylum of chordates. Chordates comes from notochord which is a firm, flexible rod of tissue located in the dorsal part of the body. In vertebrates the notochord develops into a brain and spinal cord.
Invertebrates Most invertebrates have bilateral symmetry which is an adaptation to a more motile lifestyle. It allows for cephalization. Radial symmetry are not very motile and drift along, allows for more access to food sources.
Cell to Embryo Cleavage- the series of cell divisions that occurs immediately following fertilization Blastula- dividing cells become a hollow ball Gastrulation- transforms the blastula into a multilaytered embryo called the gastrula
Germ Layers Ectoderm- outer layer of the gastrula Forms the outer layer of skin, hair, nails and the nervous system Mesoderm- middle layer Forms the skeleton, muscles, inner layer of skin, circulatory system and the lining of the body cavity Endoderm- inner layer Forms the urinary and reproductive systems, and the digestive tract; pancreas, liver, lungs and gills