Protostome Animals(animals that form mouth first) Animal Kingdom Protostome Animals(animals that form mouth first)

What is an animal?

What is an animal?

What is an animal?

What is an animal? Multicellular Heterotroph Develops from an embryo Eukaryotic Most reproduce sexually Highly structured Can move

How are animals classified?

Structure of Animals

How are animals classified? At least 4 million animals 40,000 species of vertebrates (fish, snakes, mammals, frogs, birds) Most animals are invertebrates (insects, beetles, jellyfish, worms) The animal kingdom is divided into 2 subkingdoms Eumetazoa – almost all living species Parazoa – 5000 species of sponges (simplest, no symmetry, no organs)

Animal Kingdom

Developmental Patterns Zygote Blastula Gastrula Archenteron Endoderm Ectoderm Mesoderm

Embryo Development All eumetazoa (true animals) begin life by dividing to form a hollow ball of cells called a blastula. The blastula folds in on itself to form the gastrula. The opening in which the cells flow is called the blastopore. The blastopore becomes the mouth or the anus.

Tube Within a Tube The hollow center of the gastrula is called the archenteron which becomes the gut. The gastrula represents the body plan of the adult It is a tube within a tube. The inner tube is the digestive tract Mouth anus

Formation of the Blastopore

Tube Within a Tube The outer tube is the body wall. Between the two tubes is a fluid filled space or cavity (coelem when lined with mesoderm cells) in which the organs hang.

Aceolomates –simplest animals (jellyfish, flatworms) have no cavity (coelem.) Pseudoceolomates – have a cavity with organs but it is not lined with mesoderm cells. (tiny worms, nemotodes)

acoelomates No cavity Jellyfish Flatworms

Pseudoceolomates Cavity with organs No mesoderm cell lining Nemotodes Tiny worms

Tube Within a Tube Coelomates – include the most complex animals (snails, earthworms, insects, and vertebrates)

Coelomates Coelomates are divided into to major groups. Blastopore becomes the mouth – protostomes Blastopore becomes the anus - deuterostomes

Formation of Blastopore

Gastrulation

Mouth First/Anus First

Protostomes Zoologists divide true animals according to the presence or absence of a coelem and according to whether the blastopore develops into a mouth (protostomes) oe an anus (deuterostomes) Protostomes include snails earthworms, spiders and insects Deuterostomes include starfish, sea urchins and vertebrates (us).

Symmetry Zoologists also classify animals according to symmetry. Radial Symmetry – can be rotated along their central axis without changing appearance. There is no left or right side. Bilateral Symmetry – left and right halves are mirror images of one another, anterior and posterior. (more complex)

Symmetry Radial Bilateral Central axis Left, Right, front, back

Symmetry

https://www.youtube.com/watch?v=k_9MTZgAhv0