15 Invertebrates

Porifera

Often, the basic animals with no tissues, no organ systems, and no hox gene (control body plan)

• complex multicellularity

• sexual and asexual reproduction

Diploblasts

develop two embryonic germ layers (ectoderm,endoderm,mesendoderm)

Triploblasts

develops a third layer (mesoderm) which arises from mesendoderm and resides between the endoderm and ectoderm

Layers of developmental tissue

• endo=inner

• meso=middle

• ecto=outer

Radial Symmetry

all diploblastic animals have radial symmetry

Bilateral Symmetry

• all bilaterally symmetric animals are triploblastic

• most bilaterians have clear-head ceph

Cnidaria

Have radial symmetry

• Cnidaria= Jellyfishes, corals, sea anemones, hydra

Protostomes

animals in which the mouth develops from the first opening in the embryo

• Lophotrochozoa

• ecdysozoa

Lophotrochozoa

put in this group if larvae

exdysozoa

put in this group because shed their exoskeleton

Platyhelminthes

type of lophotrochozoa. Flatworms, tapeworms, flukes

• only acoelomates that don’t have body cavity

Mollusca

type of lophotrochozoan.

Octopus, cuttlefish, clams, snails, slugs, squid

• soft bodies

• early coelomates

• many excrete calcareous shells to protect soft body

• 2nd most species of any animal phylum

Annelida

type of lophotrochozoa. Earthworms, leeches many marine forms

• early segmented body plan

Segmentation

found in three phyla annelids, arthropods, chordates

• evidence found from convergent evolution

• helps these three by having robust development

• improved locomotion

• developmental modularity where it can modify sub parts of body without affecting others

Nemerteans

type of lophotrochozoa. Ribbon worms

• similar to flatworms can reproduce by fragmentation

• separates males and females

• eversible proboscis for feeding

Rotifers

type of lophotrochozoa. oldest asexual animals (bdelloids rotifers)

Nematoda

round worms type of ecdysozoa.

• alot in soil from like thousands

• many mammal parasites like trichinella causes trichinosis from uncooked meat

• dog heartworm

Arthropoda

type of ecdysozoa. Joint footed meaning

• most diverse animal phyla

• 4 major groups (crustaceans, arachnids, myriapods, hexapoda

arthropod exoskeleton

present in all arthropods.

• benefits are protection, provides mechanical support, prevents desiccation

• doesnt grow with organism

• must be molted shed for arthropods to grow

• arthropods and fungi both have chitin cell wall

tardigrades

type of ecdysozoa. Water bears

• dormancy can survive extreme enviroments

• very small -5um or less

• live in humid places/moss

Echinoderms

type of deuterostoma, diff from two major groups. “spiny skin”

• sea stars, sea cucumbers, sea urchins, sand dollars

• re-evolved radial symmetry

• some are bilateral but become radial adults

Chordata

type of deuterostoma. Nerve cord.

• Tunicates, lancelets, vertebrates

Major evolutionary transitions

Multicellular/specialized cells
• Tissues
• Radial symmetry
• Bilateral/Triploplastic
• Body cavity
• Protostome vs. Deuterostome