what is the closest relative to animals?
Protists - choanoflagellates
when did the first animal appear?
700 million years ago
what are some shared features of animals?
- group of eukaryotic, multicellular organisms that feed by ingestion. - we all start as a fertilized egg that undergoes cell division
protostome
an organisms first opening to form is the mouth.
deuterostome
an organisms first opening to form is the anus, the mouth is formed second
embryonic germ layers
as animals develop, cells differentiate into three types
triploblastic
animals with three germ layers
diploblastic
animals with two germ layers
Porifera
not true animals, they do not have tissues, they are sponges, they completely lack symmetry, and they are collection of different types of cells.
types of symmetry in animals
- No symmetry - radial symmetry - bilateral symmetry
what are the 5 animal groups?
1. Porifera 2. Cnidaria 3. Lophotrochozoa 4. ecdysozoa 5. deuterostomia
Cnidaria
include jellyfish, and coral. radial symmetry only 2 germ layers protostomes found in water
Lophotrochozoa
earthworms, flatworms, leeches bilateral symmetry three germ layer protostomes live in the oceans and on land
Ecdysozoa
arthropods and nematodesbilateral symmetry three germ layer protostomesocean and land.
Deuterostomia
vertebrates and echinoderms (sea stars, sea urchins) bilateral symmetry three germ layers deuterostomes oceans and on land
Chordates
closely related echinoderms deuterostomes with bilateral symmetry and three germ layers
who belong in the phylum chordata?
- cephalochordates - Urochordates - Vertebrates
characteristics of chordates?
- notochord (flexible rod of fluid-filled cells wrapped in fibrous material) first part of the endoskeleton to form during development
dorsal hollow?
nerve cord is dorsal tot eh digestive tract and it is hollow
pharyngeal slits or clefts?
used for filter feeding they gave rise to structure of the ears, tonsils
traits in cephalochordata?
they retain the post-anal tail, pharyngeal slits, dorsal hollow nerve cord, notochord
blastocyst
a whole ball of cells, which is how most animals start off. Beginning developments of the opening of a part of the body