Principles of Animal Biology

alimentary canal animals appear Arthropod become birds blood body bones called carrying cavity cells century changes Chapter characteristic characters chromosomes Class colour common completely connected contain continuous crossed definite divided division dorsal existence experiment fact factors females fertilised fibres fishes frog Genera gill gives glands grey half head heart human illustrate important includes individuals inheritance insects known later light limbs living male Mammals mated material matter mouth muscle mutant natural nerve nervous normal occur offspring Orders organs origin oxygen pair parents placed plants present principle problem produced properties pure purple referred region relation represented reptiles respect response result segments selection separate side similar single skin skull species stage structure surface term tion tissue true units veins Vertebrates vestigial wall wild type