BIO-Lab 7: Protostomes

Protostomes

Eumetazoa, Bilateria, determinate, mesoderm “splits”, ecdysozoa and lophotrocozoa

Superphylum Ecdysozoa

bilaterally symmetrical, triploblastic, all members of this clade shed their outer body covering, contain nematoda, arthropoda

Examples of Ecdysozoa

roundworms, vinegar eels, millipede (class diploda), centipede (class chilopoda), crabs, lobsters, crayfish, barnacles, shrimp, isopods, branchiopods

Phylum Arthropoda

jointed appendages, complete digestive track, dioecious, ventral nerve cord,

Superphylum Lophotrocozoa

bincreased cilia, many (not all) have spiral cell division/cleavage in their embryos

lophophore

crown of ciliated tentacles that surround the mouth used for feeding

Trochophore

ciliated larval stage of annelids & molluscs, some others

Examples of Lophotrocozoa

flatworms, planarians, tapeworms, tubeworms, earthworms, leeches, chiton, clams, oysters, scallops, mussels, squid, octopus

Planarians

free-living predators or scavengers, have protonephridia used for osmoregulation, “eyespots” - photoreceptive neurons (ocelli), protrusible pharynx used for eating+ voiding feces

Tapeworms

internal parasites, definitive host is a vertebrate, no digestive system, attachment organ called a scolex

members of lophophorates

brachiopoda, mollusca (trochophore) , annelida (trochophore), ectoprocta, rotifera, plathelminthes

members of ecdysozoa

nematoda, arthropoda

Compare segmentation in annelids and arthropods

annelids are separately segmented with each segment containing chaetae while arthropods have segments that may be fused together through tagmosis and have a pair of jointed appendages at each segment.

what is the functional importance of molting in ecdysozoans?

let’s them grow and enables continuous growth, as well as supports life cycle changes such as metamorphosis such as for arthropods.

What are the 3 major differences between the Protostomes and Deuterostomes? Which animals in class were considered which?

protostomes have spiral and determinate cleavage and their blastophore develops from the mouth rather than the anus and they have a ventral nerve cord rather than a dorsal nerve cord. In class, leeches, earthworms, and centipedes were considered protostomes while starfish, sea cucumbers, and fish were considered deutorostomes.

Nemata

worm-shaped, complete gut, lacks circulatory system, longitudinal muscles only (moves by undulation), pseudocoelomate

Arthropoda

segmented bodies w/ pair of jointed appendages at each segment, suceeded and diversified through process of segments fusing together (tagmosis), ventral nerve chord, cephalized ganglia, complete gut, open circulatory system

Plathyelminthes

flatworms, cephalized cerebral ganglia, ladder-like nervous system, acoelomate, incomplete complex gut, no circulatory system

Mollusca

mantle, mantle cavity, large, muscular foot, specialized feeding structure (radula), open circulatory system, complete gut, trochophore

Annelida

segmented w/ each segment containing chetae, complete gut with regional specialization, closed circulatory system, well developed nervous system w/ cerebral ganglion, ventral nerve chord, characteristic trochophore

Brachiopoda

lophophore, mantle that secretes a calcerouous shell, forms mantle cavity, setae that extend out from the shell, open circulatory system, only lophotrochozoa with radial cleavage