chapter 12 Flashcards
animals are divided into what 2 subgroups?
invertebrates (withought backbones)
vertebrates (with backbones)
what is a grastrula?
a stage of embryo development in which germ layers are formed
what is a coelom? what structures can be found in higher organisms?
a body cavity or space lined with a layer of cells called the peritoneum
in higher organisms= mouth and anus
peritoneum and pseudocoelom?
peritoneum=a covering membrane that lines the body cavity and covers the internal organs
pseudocoelom= a fluid filled cavity that lacks the mesodermal lining of a true coelom
what are the 3 main layers of tissue found in many of the animal groups?
ectoderm(outside,skin/receptions)
endoderm(inside,digestion)
mesoderm(houses reproductive musculature excretory systems)
what is symmetry? what are 2 of them?
symmetry = the balanced distribution of duplicate body parts or shapes within the body of an organism
bilateral symmetry: where the body displays left and right halves that are mirror images of eachother ex. fish
Radial symmetry: symmetrical about a central axis (in one plane) ex.hydra
what is cephalization? what is the simplest animal to display this?
refers to the concentration of nerve tissue and receptors at the anterior end of an animal’s body
simplest animal =fish, the head always enters a new environment first
sessile
animals remain fixed in one place throughout their adult lives and are not capable of independent movement
hermaphroditic
an organism that contains both male and female sex cells or organs
larva
a juvenile form that looks very different from the adult
metamorphosis
a process in which a larval form drastically changed shape to become more like the adult
what are 2 methods of asexual reproduction in hydra?
budding and regeneration
what is a scolex?
the know like head of a tape worm
what is a proglottid?
the segment like divisions of a tapeworm’s body
how is the flatworm adapted for parasitic lifestyle?
large # of eggs
having an intermediate host
has a scolex
hermaphroditic
and don’t have a complex digestive system
