BIOL113 L24

Invertebrates

Animals without a backbone.

Animal

Multicellular, heterotrophic eukaryotes with tissue that develops from embryonic layers.

Five criteria for animals

Multicellular, heterotrophic eukaryotes; lack of cell walls; presence of nervous and muscle tissue; sexual reproduction; formation of blastula.

Organic molecule acquisition in animals

Through ingestion or decomposing organic material.

Structural support in animal cells

Provided by extracellular proteins, especially collagen.

Animal tissues

Nervous tissue for impulse conduction and muscle tissue for movement.

Animal reproduction

Primarily sexual, with small flagellated sperm fertilizing a larger, nonmotile egg.

Diploid stage in animal life cycle

Zygote.

Multicellular ball of cells in cleavage

Blastula.

Animal kingdom origin

From a colonial, flagellated protist.

Estimated age of animal kingdom ancestor

Over 770 million years ago.

Colonial flagellated protist

Likely ancestor of animals which is likely to be related to choanoflagellates, a group that arose about a billion years ago.

Animal evolution hypothesis

Colony of cells evolved into a hollow sphere, then specialized into layers.

Fungi nutrition

Heterotrophic, digesting food externally.

Animal characteristics

Multicellular, heterotrophic eukaryotes.

Carbohydrate reserves in animals

Stored as glycogen.

Impulse conduction and movement in animals

Nervous and muscle tissue.

Challenges for animals

Oxygen extraction, nourishment, waste excretion, and movement.

Long-term adaptation in animals

Achieved through natural selection.

Animal relationships based on

Body plans and embryonic development.

Major grades in animal phylogenetic tree

Distinguished by structural changes at deep branches.

First branch point in animal phylogenetic tree

Splits Parazoa from Eumetazoa.

Radiata members

Phylum Cnidaria and Ctenophora.

Bilateria symmetry

Bilateral with dorsal, ventral, anterior, posterior, left, and right sides.

Cephalization

Concentration of sensory equipment on the anterior end.

Cephalization components

Central nervous system in the head extending to the tail.

Animal symmetry and lifestyle

Radial for sessile, bilateral for moving animals.

Germ layers

Embryonic tissue layers forming organs.

Radiata germ layers

Diploblastic with two layers.

Ectoderm role

Forms outer covering and central nervous system in some phyla.

Endoderm role

Forms digestive tract lining and associated organs.

Bilateria germ layers

Triploblastic with mesoderm for muscles and organs.

Acoelomates

Solid-bodied organisms lacking a body cavity.

Pseudocoelom

Body cavity partially lined by mesoderm.

Coelomates

Organisms with a true, mesoderm-lined body cavity.

Body cavity functions

Cushioning organs, hydrostatic skeleton, organ movement.

Coelomate phyla division

Protostomes and deuterostomes based on development differences.

Spiral cleavage

Diagonal cell division to embryo axis.

Determinate cleavage

Early cell fate determination.

Radial cleavage

Cleavage planes parallel or perpendicular to egg axis.

Indeterminate cleavage

Each cell retains capacity to develop into an embryo.

Coelom formation start

Gastrula stage.

Schizocoelous development

Mesoderm splitting to form coelomic cavities in protostomes.

Enterocoelous development

Mesoderm hollowing to form coelomic cavities in deuterostomes.

Protostome blastopore fate

Develops into mouth in many cases.

Deuterostome blastopore fate

Usually develops into anus, mouth from secondary opening.