Evolution of body plans Flashcards
Body plan
Basic structural design of a particular animal group
Symmetry
Asymmetric (0), radially symmetric (any plane along main body), bilaterally symmetrical (1)
Synapomorphy
Shared derived trait. Basis for phylogenetic (may be convergent evolution). molecular phylogenetic also used
Traits supporting monophyly of animals
Multicellular, single-celled zygote, heterotrophic, contractile muscles, gene sequences, Hox gene function, cell junction similarity, ECM - collages, proteoglycans
Simple: placozoa
1mm diameter, marine, multicellular, simple epithelium enclosing loose sheet of stellate cells, bear flagella to crawl along sea floor
Types of simple
Placozoa, porifera (sponges), etnophora (comob jellies), cnidaria (hydrozoans, sae anemones, jelly fish, corals_
Germ layers of embryo: one layer
Placozoa, porifera
Germ layers of embryo: two layers
Diploblastic - endo/ectoderm: ctenophora, cnidaria
Germ layers of embryo: three layers
Triploblastic - endo/meso/ectoderm: protostomes and deutersotomes; coelomate, pseudocoelomate, coelomate
Protostomes
Embryonic blastopore -> mouth, radial cleavage ancestral, asymmetric, some spiral cleavage, bilaterally symmetrical, entrance to digestive tract anterior to brain, ventral NS, circulatory system missing or open/closed. 2 classes and 1 unclassified group
Protostomes: lophotrochoza
Grow by adding to skeleton - lophopre structure for feeding, internal hydrostatic skeleton
Phylum byozoa: marine, sessile, colonial, feed using lophophores and beating cilia on tentacles, AS and sometimes filler feeders
Other phylums: photon, brachiopod, platuhelminthes (flatworms), rotifera, nemertea (ribbonworms), annelida (classes: oligochaete, polychaeta, hiradinea), mollusca
Protostomes: chaetognartha (arrow worm)
Phylogeny debated, sister group to lophotrochozoa?, marine, planktonic, column, no trochophore larvae, no circulatory system
Protostomes: ecdysozoa
exoskeleton, moulting, grow ecdysis - ways to feed
Phyla: nematoda (roundworms), onchophora (velvet worms), chelicerata (spiders), crustacea, myriapoda, hexapoda
Deuterostomes
Embryonic blastopore => anuc, radial cleavage
Deutrostomes: phyla
Echinodermata, hemichordata, chordata (classes: urochordata, cephalocordata - subphylum vertebrata)
Paratism
Non-metal relative organisms - benefits at cost of other
Ectoparasite
Lives on surface of host
Endoparasite
Lives within host
Parasitoid
Organism spends most of life in single host and kills host
Pathogen
Organisms causing disease in host
Vector
Organism transmits pathogen e.g. anopheles mosquito carries malaeria
Platyhelminthes: classes
Monogenea - skin flush - hooks for attaching; trematoda - endoparasites with complex life cycles - 2 replication life stages - snail fever, snail and vertebrate host; cestoda (tape worms) - vertebrate - no gut, feeds by absorbing part-digested carbohydrate to inhibit host digestive enzymes; nematoda - mouth -> buccal cavity, many have teeth, muscular pargynx, grow by malting (ecdyosozoan), many larval stages; crustacea - copepoda and cirripedia (barracks) - ectoparasites