24.2 Animal Body Plans

PRESENTATIONS 24.3 Sponges and Cnidarians – T.J. (Thur, May 29) 25.1 Flatworms - Jimmy (Thur, May 29) 25.2 Roundworms and Rotifers - Joe (Fri, May 30) 25.4 Segmented Worms (Annelids) - Crisanta (Fri, May 30) 25.3 Molluscs - Larissa (Tuesday, June 3) 26.1 Arthropod Characteristics - Jack (Tuesday, June 3) 26.2 Arthropod Diversity - Chinzorig (Wednesday, June 4) 26.3 Insects + Their Relatives - Lauryn (Wednesday, June 4) 27.1 Echinoderms Characteristics (Monday, June 9) 28.1 and 28.2 Fishes - (Tuesday + Wednesday, June 10 + 11) 28.3 Amphibians – (Thursday, June 12)

DISSECTIONS 25.2 Roundworms and Rotifers - Monday, June 2 (Ascaris) 25.4 Segmented Worms (Annelids) - Monday, June 2 (Earthworm) 25.3 Molluscs - Friday, June 6 (Clam, Squid) 26.1 – 26.3 Arthropod Characteristics - Monday, June 9 (grashopper, crayfish) 27.3 Echinoderms Characteristics – Tuesday, June 10 (sea star) 28.1 - 28.2 Fishes - Thursday, June 12 (perch) 28.3 Amphibians - Thursday, June 12 (frog) maybe

Evolution of Animal Body Plans Anatomical features in animals’ body plans mark the branching points on the evolutionary tree. For example, animals without tissues are grouped separately from animals with tissues, and animals without segments are grouped separately from animals with segments. Recall the relationships among animals on this tree are inferred by studying similarities in embryological development and shared anatomical features. However, molecular data (DNA, ribosomal RNA, and proteins) suggest other relationships among animals

Development of Tissues Which animals have no tissues? Tissues mark the first branching point on the evolutionary tree Sponges are the only animals without tissues They are on the no-true-tissues branch. All other phyla branch off from the tissues branch of the tree.

Body Symmetry Asymmetry Radial Symmetry Bilateral Symmetry The first branching point off the tissues branch Symmetry describes the similarity, or balance, among body structures The type of symmetry defines the kind of movements the animals can make Asymmetry Radial Symmetry Bilateral Symmetry

ASSYMETRY NO SYMMETRY at all = their shapes are not regular Examples: ?? Sponges, corals

RADIAL SYMETRY Some animals have two halves that look almost the same when the animal is divided along any plane through its central line This is radial symmetry. Examples: ?? Jellies, sea anemones…

Crown Jellyfish

Soft Coral Polyps

BILATERAL SYMETRY Animals with bilateral symmetry have two halves that look like mirror images when the animal is divided along only one plane through its central axis. Examples: ?? birds, dogs, humans…

Candy striped Annelid

Blue Spotted Sting Ray

Marine Flatworm

BILATERAL ASSYMETRY African Elephants

Which cell layers are involved in development? BILATERAL ASSYMETRY Which cell layers are involved in development? Most animals with radial symmetry develop from two cell layers—the ectoderm and the endoderm All animals with bilateral symmetry develop from three cell layers—the ectoderm, the endoderm, and the mesoderm

What is the body plan called CEPHALIZATION? An animal with bilateral symmetry has a head end and a tail end.

What is the body plan called CEPHALIZATION? An animal with bilateral symmetry has a head end and a tail end. The head end is called the anterior end. The tail end is called the posterior end. When the nervous tissue and sensory organs are located at the anterior end, the body plan is called CEPHALIZATION Most animals with cephalization move with their anterior ends first

What is the body plan called CEPHALIZATION? An animal with bilateral symmetry also has a backside and an underside. The backside is the dorsal surface. The underside, or belly, is the ventral surface

Body Cavities An animal with bilateral symmetry also has a gut where food is digested. The gut is either a sac inside the body or A tube that runs through the body

Body Cavities A saclike gut has one opening: the mouth The mouth takes in food and disposes of wastes Examples: sponges, jellyfish, flatworms

Body Cavities A tubelike gut has an opening at each end Food is taken in at the mouth and digested, nutrients are absorbed, and waste is then excreted through the anus.

Body Cavities Pseudocoelomate Acoelomate Coelomate

Acoelomate Pseudocoelomate Coelomate

Acoelomates An acoelomate (ay SEE lum ate) is an animal that does not have a fluid filled body cavity (it has only digestive cavity) This animal has a solid body with no circulatory system. Nutrients and wastes spread from one cell to another.

Pseudocoelomates The pseudocoelom (soo duh SEE lum) is a fluid filled cavity that forms between the mesoderm and the endoderm. This position limits tissue, organ, and system development

Coelomates Most animals with bilateral symmetry have a fluid filled cavity between the gut and the outside body wall called a coelom (SEE lum). The coelom and the organs within it form from the mesoderm. The coelom was an adaptation that enabled coelomates to develop larger and more specialized body structures for increased nutrient and waste transport.

Development in Coelomate Animals Coelomates branch into two lines of development: Protostomes Deuterostomes Biologists compare how embryos develop to decide if animals are closely related.

PROTOSTOME Development The mouth of a protostome develops from the first opening in the gastrula. Also, during development, the mesoderm splits down the middle, forming a coelom between the pieces.

Deuterostome Development In a deuterostome, the anus develops from the first opening in the gastrula. The mouth forms from another part of the gastrula Also, during development, the coelom forms from two pouches of mesoderm.

Segmentation A segmented animal has a series of sections that are exactly alike

Segmentation A segmented animal has a series of sections that are exactly alike Segmentation has two advantages: Other sections might be able to perform the function of a damaged section, enabling the animal to survive. Segments can move independently. This enables flexible and complex movement.

HOMEWORK/CLASSWORK 24.2 Reading Notes 24.2 Study Guide