2014 Module7 Animalia print - University of San...

What is an animal?

•  Mul.cellular heterotrophs: feed by inges&on.

•  How does this differ from plants, fungi, pro.sts?

What is an animal?

•  Carbohydrates stored as glycogen

•  Polysaccharide of glucose

•  (no, you do not need to know this structure)

What is an animal?

•  No cell walls •  Cells supported by structural proteins: collagen –  Extracellular matrix, supports .ssues, gives cells structure from outside

–  Triple-‐helix structural protein

What is an animal?

•  Nerve and muscle .ssue

•  Impulse & movement

What is an animal?

•  Generally, most have sexual reproduc.on from anisogamous or heterogamous gametes.

What is an animal?

Development •  Egg + Sperm ⇒ •  Zygote ⇒cleavage ⇒ •  Blastula ⇒ •  Gastrula ⇒ •  Larva or juvenile ⇒ •  Adult

•  This development regulated by Hox genes

Animal Diversity •  The vast majority of animal

species are marine •  Only truly terrestrial*

animals come from 5 phyla –  Mollusca –  Annelida –  Onychophora –  Arthropoda –  Chordata

•  *Does not include internal parasites nor taxa needing constant external moisture

Animal Origins

•  Monophyle&c •  Sister taxon Choanoflagellates (pro.st protozoan) •  Colonial, flagellated pro.st ancestor

Animal Origins

•  Gastrula-‐like infolding into two layers

•  Increased specializa.on of cells and .ssues beginning with soma&c vs reproduc&ve

Animal Origins •  Molecular evidence: – Suggests divergence from fungi ~1 bya – Common ancestor of animals 675-‐875 mya

Animal Origins

•  Fossil evidence: –  Possible trace fossils ~900 mya

–  Ediacaran fauna 610-‐550 mya •  Animals???

–  Definite animal fossils (about 1/2 of phyla) appear during Cambrian Explosion.

Animal Origins The Cambrian Explosion

•  Why so sudden? 1.  Predator-‐Prey interac.ons and

coevolu.onary arms races. 2.  Increase in atmospheric oxygen

allows for larger animals with higher metabolic rates.

3.  Key innova&on of Hox genes allows rapid diversifica.on of developmental pathways.

Morphological Trends Symmetry

•  Radial vs bilateral •  Radial –  Top and bofom only-‐-‐no leg or right

–  Likely ancestral trait: Cnidarians, Ctenophores

Morphological Trends

Symmetry •  Radial vs bilateral •  Bilateral –  Top-‐bofom, forward-‐backward, leg-‐right

–  Allowed cephaliza&on, more ac.ve lifestyle.

Morphological Trends

Tissues •  Porifera or Parazoa (sponges) lack true .ssues (this is a unique development)

Gastrula.on

•  Germ layers are formed by the process of gastrula&on

•  One end of blastula folds inward, eventually produces layers of embryonic .ssue

Gastrula.on

•  Blastula is a mul.-‐cellular embryonic stage that is typically a hollow ball of cells that surrounds a cavity called a blastocoel

Gastrula.on

•  The invagina.on or gastrula.on results in the gastrula stage

•  The pouch formed is called the archenteron and the opening to the outside is called the blastopore

Gastrula.on

•  Animals with only ectoderm and endoderm have only gastrula.on as germ layer forma.on

•  Cnidaria (jellies) and Ctenophora (comb jellies)

•  Diploblas&c

Gastrula.on

•  All bilateral animals have a third germ layer, the mesoderm

•  Forms muscles and most organs between diges.ve tract and the outer covering.

•  Triploblas&c

Body Cavity: The Coelom

•  Most triploblas.c animals have a body cavity –  Fluid-‐ or air-‐filled space separa.ng the diges.ve tract from the outer body wall.

•  This is the coelom


•  The coelom forms from .ssue derived from mesoderm

•  COELOMATES: –  Mesoderm connects

dorsally and ventrally and provides a complete lining of the coelom



•  PSEUDO-‐COELOMATES: –  Coelom is lined with mesoderm (outside) and endoderm (inside)



•  ACOELOMATES: –  No true body cavity –  Ogen sog-‐bodied organisms.


•  All three groups (Coelomates, Pseudocoelomates, and Acoelomates) are polyphyle&c.

•  Body cavity (coelom) also coincides with complete diges.ve tract (mouth, anus) and circulatory system (vessels or sinuses)

Coelomates: Protostomes & Deuterostomes

Classic division in Bilateria

Differences •  Pafern of early cell division •  To&potency in early cell development •  The forma.on of the coelom •  Fate of the blastopore

Coelomates: Protostomes & Deuterostomes Protostomes

•  Early cell division is via spiral cleavage

Deuterostomes •  Early cell division is via radial cleavage

Coelomates: Protostomes & Deuterostomes Protostomes

•  Fate of cells is determined at early cleavage stages: Determinate cleavage

Deuterostomes •  Cells at early cleavage

stages remain to&potent: Indeterminate cleavage


Protostomes •  Solid mass of

mesoderm splits to form coelom: schizocoelous

Deuterostomes •  Coelom forms from

mesodermal outpocke.ngs of the archenteron: enterocoelous


Protostomes •  Blastopore

becomes mouth

Deuterostomes •  Blastopore

becomes anus

General Classifica.on of Animalia

•  Currently considerable debate on rela.onships between animal phyla.

•  Remember, Animalia is monophyle.c.


•  Sponges branch first, form the Porifera or Parazoa. –  Morphology and

molecules disagree about monophyly

–  Generally considered paraphyle.c

–  Animalia without true .ssues

•  Everything else form Eumetazoa –  Animalia with true .ssues


•  Radiata are paraphyle.c: Cnidaria & Ctenophora –  Radial symmetry –  Diploblas.c

•  Bilateria are monophyle.c –  Bilateral symmetry –  Triploblas.c

General Classifica.on of Animalia •  Bilateria divided into four

groups: –  Acoela –  Deuterostomia

•  Echinodermata •  Chordata

–  Ecdysozoa •  Nematoda •  Arthropoda

–  Lophotrochozoa •  Platyhelminthes •  Ro.fera •  Ectoprocta •  Brachiopoda •  Mollusca

2014 Module7 Animalia print - University of San...

Documents

Transcript of 2014 Module7 Animalia print - University of San...