Biodiversity II; Unit 3: Biodiversity

Characteristics of Animals

• multicellular

• heterotrophic

• cells lack walls

• have tissues (most) and can move at some point in their life

• sexual reproduction

• specialized sensory structures and nervous system

• blastula stage during development

What life cycle do animals use?

Gametic

Are animals diploid or haploid?

Diploid; minus gamete phase

Is there a multicellular haploid phase in animals?

No

Cleavage

The early process in which cells divide; a kind of mitosis.

Gastrulation

The process in which the cell begins to be pushed into, in the form of a tube, which then leaves and opening.

Complete Gastrulation

The process in which the “tube” goes all the way through, connected to the outside world on both ends; this gives rise to two or three germ layers. This tube becomes the digestive system; one end is the mouth, the other is the anus.

Radial Symmetry

Body type in which the mouth is the center and the body radiates around it.

What are the two major branches within the Eumetazoa clade?

Deuterosomes and Protozotomes

Which period had the largest amount of animal diversity?

The Cambrian period

Cambrian Explosion

(541-485 mya); period of time where animal diversity largely increased, giving

Why was the Cambrian period favorable for these changes?

1. Favorable environmental conditions

2. Evolution of the Hox gene complete

3. Evolutionary “arms race” between predator and prey

Homeotic Genes

Genes that regulate the development of entire segments of the body

Devonian Period

Period in the Paleozoic era; the evolution from water to land.

Mesozoic

The age of the dinosaurs, ended due to meteor and environmental factors.

Cenozoic Era

Age of the mammals; mammals were always present, just underground due to ecological niches not being available.

What is animal classification based on?

1. Presence or absence of tissues

2. Body symmetry

3. Patterns of embryonic development

What are two key features that bilateral animals have?

1. Cephalization

2. Dorsal (top) and ventral (bottom) ends

Cephalization

The development of a head

Tissues

A collection of specialized cells isolated from other tissues by membranes

What is the only animal group without tissues?

Sponges

Eumetazoa

Animals with more than one tissue layer that develops from 2 or 3 germ layers.

How can animal body plans be organized by? (tissue-related)

1. Endoderm

2. Ectoderm

3. Mesoderm

Ectoderm

Animals that have an outer covering and (in some) CNS

Endoderm

Animals that have a lining of digestive tract, liver, and lungs.

Mesoderm

Animals that have muscles and most organs besides their digestive tract.

Germ Layer

A layer of devel

How many layers do radial animals have?

2 germ layers (diploblastic)

How many layers do bilateral animals have?

3 germ layers, triploblastic

Blastopore development in Protostomes

The blastopore develops into the mouth (mouth first).

Blastopore development in Deuterostomes

The blastopore develops into the anus (mouth second).

Spiral/determinate Cleavage

Cleavage within Protostomes; cell fate is set

Radial/indeterminate Cleavage

Cleavage within Deuterostomes; cell fate is flexible or totipotent

Coelom

A true body cavity derived only from mesoderm animals.

Coelomates

Triploblastic animals that have a true body cavity.

Pseudocoelomate

Triploblastic animals that possess a false coelom; a pseudocoelom forms between the mesoderm and endoderm layers and functions like a true coelom.

Acoelomates

Triploblastic animals that lack a body cavity.

Phylum Porifera— Sponges

Multicellular animals that lack real tissue and symmetry; they can reproduce both asexually and sexually.

Phylum Cnidaria

Diploblastic, mostly marine animals that have radial symmetry due to incomplete gastrulation; they have tissues, a simple nervous system, and use their gastrovascular cavity for extracellular digestion.

What are the two body forms Cnidarians have?

1. Polyps: sessile benthic

2. Medusa: possess some swimming abilities

Do Cnidarians possess a central control organ (e.g.: brain)?

No, they do not.

Cnidarian Respiration

Described as through the body covering and gastrovascular cavity; simple diffusion is used to allow nutrients and gases to travel throughout the digestive system.

Cnidocysts

Cells that contain nematocysts which discharge toxins, and are used to catch prey and as a defense line.

4 Major Classes of Phylum Cnidaria

1. Hydrozoans

2. Scyphozoans

3. Cubozoans

4. 
   

Sexual Reproduction in Cnidaria

Slightly different for all cnidarians; exhibit poly, medusa, or both. Gametes are released into a water column, often timed with the full moon.