intro to animaliachapter 30

• animal characteristics• multicellular heterotrophs

• origins?• syncytial ciliate hypothesis, colonial flagellate hypothesis• polyphyletic origin?• molecular evidence?

OTHEREUKARYOTES

Choanoflagellates

Sponges

Other animalsA

nim

als

Individualchoanoflagellate

Collar cell(choanocyte)

animal themes• comparative morphology / development

• origin of tissues• body cavity• nervous systems / symmetry• metamerism• ontogeny / embryonic development

• body cavity -- coeloms• acoelomate -- • pseudocoelomate • eucoelomate --

CoelomBody covering

(from ectoderm)

Digestive tract(from endoderm)

Tissue layerlining coelom

and suspendinginternal organs

(from mesoderm)

Coelomate

Acoelomate Body covering(from ectoderm)

Wall of digestive cavity(from endoderm)

Tissue-filled region

(from mesoderm)

Pseudocoelom

Body covering(from ectoderm)

Muscle layer(from

mesoderm)

Digestive tract(from endoderm)

Pseudocoelomate

symmetry• body arrangement

• radial symmetry -- • biradial symmetry?

• bilateral symmetry --

RADIAL SYMMETRY

BILATERAL SYMMETRYBIRADIAL SYMMETRY

segmentation• metamerism

• probably evolved 3 times• panarthropoda• chordata• annelida

• advantages:• efficient locomotion• tagmatization• redundancy

traditional classification• Tissue Layer and Body Cavity Evolution/Development

• Radiata—• Diploblastic, Acoelomate

• Bilateria—all other phyla• Triploblastic• Acoelomate—Platyhelminthes…• Pseudocoelomate—Rotifera, Nematoda…• Eucoelomate—all other animal phyla

• protostomes (monophyletic group?)• spiral cleavage• schizocoely• protostomous• determinate cleavage

• deuterostomes (probably a monophyletic group)• radial cleavage• enterocoely• deuterostomous• indeterminate cleavage

spiral

radial

• Traditional classification:• Protostomes—acoelomate, pseudocoelomate, eucoelomate• Deuterostomes—all eucoelomate

• Molecular studies support:• Protostomes -- monophyletic group?• Lophotrochozoa (platy, nemert, rotif, annel, others)• Ecdysozoa (nemat, arthro, pentastomida, others)

• Deuterostomes—Chordates, Hemichordates, Echinoderms

ANIM

ALIA

segmentation

segmentation

segmentation

radial symmetry

protostomous

coelom?, CNS?, cephalization

bilateral symmetry

multicellularity

BILA

TERI

A

PORIFERA

CNIDARIA

CTENOPHORA

ACOELA

ROTIFERA

PLATYHELMINTHES

ANNELIDA

MOLLUSCA

NEMATA

ARTHROPODA

ECHINODERMATA

CHORDATA

CHOANOFLAGELLATES

DEUTEROSTOMIA

ECDYSOZOA

LOPHOTROCHOZOA

?

PORIFERA• Phylum Porifera—porus-pore, fera-bearing

• Pinacocytes• Mesohyl (Spongin, Spicules)

• Archaeocytes—ameboid cells• Choanocytes— “collar” cells

choanoderm

mesohyl

pinacoderm

PORIFERA• Body form—

• Asconoid• Syconoid• Leuconoid

• reproduction• asexual• sexual

ASCONOID

SICONOID

LEUCONOID

CNIDARIA• Phylum Cnidaria—knide – nettle, aria – pl. of “like”

• Cnidocytes• Radial symmetry• Tissues - simple organs• Diploblastic• classes:

• Hydrozoa• Anthozoa• Cubozoa• Scyphozoa

CNIDARIA• Life Cycle / Body forms

• Polyp • budding• Species with reduced or

absent medusae have sexual polyps

• Medusa • typically dioecious

(gonochoristic)

adult medusa

sperm

egg

planula

strobila

ephyra

scyphistoma

youngstrobila

CTENOPHORA• Phylum Ctenophora—“comb-bearing”

• Bi-radial symmetry (paired tentacles, double internal canals), • diploblastic• anatomy

• Collenchyme• Comb plates• Tentacles• Colloblasts

• Sexual reproduction (monoecious)

ACOELA• phylum acoelomorpha

• marine or brackish• usually found in sediments

• Digestion• some with gastrovascular cavity

• Reproduction • Radial nerve system

proboscis sheath

statocyst

testes

gut

mouth

ovary

gonopore