origins? intro to animalia · porifera •phylum porifera—porus-pore, fera-bearing •pinacocytes...
TRANSCRIPT
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