```                                                     PRIMITIVE ANIMALS

4/4/94, 4/3/95, 4/3/96, 4/7/97, 4/6/98, 3 Apr 00, 4 April 01, 1 Apr 02, 7 Apr 03, 5 April 04, 5 April 2005, 7April08

Campbell’s 6<sup>th</sup>: 633-662, 7<sup>th</sup>: 626-650

EVOLUTIONARY TRENDS IN ANIMALS p 634-639:

TRAITS                                     PRIMITIVE       ADVANCED

1) Number germ layers               Two                     three (endoderm, mesoderm and ectoderm)             627

2) type of body symmetry           radial                    bilateral                                                                     630

3) development of head              no head                cephalization (condition of having a head...) 

4) type of GI tract                       two-way GI tract  one-way gastrointestinal tract                                         

5) presence of coelum                 none                     possess coelum (hollow chamber):                          631

                                                                                 allows dev of organs and

                                                                                 hydroskeleton:

                                                                                           motility of organs in stationary animal

                                                                                           protects organs with water shock absorber

6) circulation                               open circulation   closed circulation (blood stays enclosed in vessels)

7) segmented body plan              un-segmented       segmented

8) nerve cord location                 ventral                  dorsal

9) structure of gastrula: p. 627         blastula with blastocoel (hollow inside ball of cells)

gastrulation: invagination forms archenteron and blastopore

p 632  protostome        blastopore becomes mouth (most animals except following deuterostome phyla)

             deuterostome    blastopore becomes anus, mouth forms at other end (only echinoderms, chordata)

PARAZOA (does not really possess tissues)

PORIFERA (p 642)               (bears pores) Sponges = sessile animals: barely any tissue specialization: marine filter feeders, no "gut", choanocytes: collar cells with flagellum, filaments, porocytes

RADIATA (radial symmetry)

CNIDARIA (p. 643)              (nettle because of stinging) Hollow gastrovascular cavity (coelenteron), radial symmetry, two tissue layers. cnidoblast, nematocysts sting, 9000 species: hydra, jellyfish, coral, sea anemones

ACOELOMATES (bilateral but without a coelum)

PLATYHELMINTHES (647)   bilateral symmetry, cephalization (ganglia for brains), three tissues, gastrovascular cavity, has organs, flame cells: excretory, pharynx, 9000 species: planarian, tapeworm from uncooked beef or pork (release proglottids, filled with eggs), liver fluke

PSEUDOCOELOMATA (hollow body, but not fully lined with mesoderm)

NEMATODA (655)               (thread forms) one way GI tract, pseudocoelum, roundworms, most numerous of all animals, millions in soil. pinworms, Trichinella

MOLLUSCA:                       p 650 (see separate sheet. Visceral mass, mantle, foot

COELOMATA (possess true coelum)

ANNELIDA (654)                 (little rings) segmented, true coelum, fluid-filled hydroskeleton, leeches,

          Earthworm:                  many identical segments, each with nephridia, setae, 2 sets muscles, long. and circular, dorsal & ventral vessel, 5 pairs of hearts, digests organic material in soil. pharynx, esophagus, gizzard, intestine, hermaphroditic