Introduction to Animals Body Plans and Symmetry

Distinguishing Plants from Animals What makes an animal an animal? What makes a plant a plant?

Vocabulary Section 1 Invertebrate Vertebrate Endoskeleton Exoskeleton Hermaphrodite Internal Fertilization External Fertilization Zygote Blastula Gastrula Endoderm Ectoderm Mesoderm

General Animal Characteristics Animals are a diverse group of consumers that share some major characteristics. All are multicellular All are heterotrophs Their cells do NOT have cell walls Most are able to move at some point in life All are diverse in form and habitat Most reproduce sexually Have characteristic patterns of embryonic development Cells of all animals with the exception of sponges, are organized into tissues.

Evolution of Animals All present day animals are thought to have evolved from choanoflagellates. Choanoflagellates were protists that formed colonies in the sea approximately 570 million years ago. Choanoflagellates are thought to be the earliest “true animal” An example is Zoothamnium.

Evolution of Animals All present day animals are thought to have evolved from choanoflagellates. Choanoflagellates were protists that formed colonies in the sea approximately 570 million years ago. Choanoflagellates are thought to be the earliest “true animal” An example is Zoothamnium.

Feeding and Digestion Animals are heterotrophs meaning they must obtain their food from plants or other organisms. Carnivores obtain energy by eating other animals. Herbivores obtain energy by eating plants. Omnivores obtain energy by eating a mixture of plants and other animals. Is this animal a carnivore, omnivore, or herbivore?

Feeding and Digestion The animal’s mouth form and structure determines how it obtains its food. Examples: A sea star pries open a clam. A butterfly drinks nectar from a flower. A sponge obtains its food through pores. A hydra paralyzes its prey before reeling it into its mouth.

Feeding and Digestion After obtaining food, animals must digest the food! Sponges digest their food inside specific cells. Humans digest their food in organs. Let’s review digestion!

Let’s take a look at some Examples! Remember to take a couple of notes on videos! https://www.youtube.com/watch?v=TfaafxnnJlY https://www.shapeoflife.org/video/echinoderms-sea-star-time-lapse-eating- mussel https://www.youtube.com/watch?v=tAC2zlLcUeg

Invertebrates Animals differ in the ways they support themselves. An invertebrate is an animal without a backbone. Many have exoskeletons(Hard/tough outer coverings that provide the framework for support). Examples: Cicada, crabs, scorpions, snails, etc. Exoskeletons serve to protect soft body tissues, protect the organism from predators, and help prevent water loss. Important note: Exoskeletons do NOT grow with the animal so it must molt and create a new one. Others contain endoskeletons such as sea stars and sea urchins.

Invertebrates Now let’s take a look at the cicada molting its exoskeleton. https://www.youtube.com/watch?v=Bw1MF dlmWyA Show class some actual molts!

Vertebrates If an animal has a backbone and an endoskeleton, the it is classified as a vertebrate. The endoskeleton provides support, protects internal organs, and provides an internal brace for muscles to pull against. An endoskeleton grows with the animal. Examples include: Sharks (made of cartilage) Fish, amphibians, reptiles, birds, and mammals (made of bone)

Vertebrate Endoskeleton

Habitats Animals have a variety of different adaptations so their habitat needs differ. Some animals may live In desserts (Mali Uromastyx) In tropical rainforests (Scarlet McCaw) In Temperate Deciduous Forest (White Tailed Deer) In the Ocean (Orcas)

Distinguish between vertebrates and invertebrates. Infer how an exoskeleton might be a disadvantage for animals.

Movement The evolution of nerve and muscle tissues allows animals to move in more complex and faster ways versus the organisms in other kingdoms. Some animals remain stationary as adults, but most have a body form that can move at some stage of development. Example: Goblet Worm

Cell Structure Animal cells do NOT have cell walls. Cells of all animals except sponges are organized into structural and functional units called tissues! Let’s review the biological levels of organization! A tissue is a specialized group of cells that perform a specific function. Examples: Blood Neurons Muscle Tissue Smooth, Cardiac, and Skeletal

Reproduction Most animals reproduce sexually; some reproduce asexually. Hermaphrodites produce both eggs and sperm in the same animal body. Generally, hermaphrodites produce eggs and sperm at different times. Example: Earthworm and clownfish Fertilization occurs when the sperm penetrates the egg. Acrosomal reaction must occur 1st. Once the sperm penetrates the egg and fertilization occurs, the fertilized egg cell is called a zygote.

Reproduction Internal fertilization occurs when the sperm and the egg combine inside the animal’s body. Examples: Turtles, Dogs, birds External Fertilization occurs when the egg and sperm combine outside of the animal’s body. Requires an aquatic environment so sperm can swim to the egg(s) Many fish and frogs

Reproduction Asexual reproduction: 1 parent produced offspring genetically identical to itself. 4 common methods of asexual reproduction: Budding: an offspring develops as a growth on the parent’s body Example: Hydra Fragmentation: parent breaks into pieces and each piece can develop into an adult animal Example: Some Sponges Regeneration: a new organism can regenerate, or regrow, from the lost body part if the part contains enough genetic information Example: Flatworm Parthenogenesis: a female animal produces eggs that develop without being fertilized. Example: Ants

Infer the advantages and disadvantages of asexual reproduction in animals. Infer why animals lay a large number of eggs when fertilization is external.

Critical Thinking If a pond in which turtles and fish are living almost dries up during a drought, what affect will this have on the animals’ ability to reproduce and why?

Early Development After fertilization occurs in most animals, the zygote will undergo mitosis and a series of cell divisions to form new cells. Embryo: after the zygote has formed 2 cells. After going through a series of mitosis and cell divisions, a ball of cells is formed. Blastula: fluid filled ball of cells Note during early development the number of cells increases but the amount of cytoplasm remains the same. The total size of the embryo does not increase during early development.

Early Development The blastula will continue to undergo cell divisions. Gastrula: a two cell layer sac with an opening at one end. Open your textbook to page 696 and study over figure 5!

Explain the differences between the blastula and gastrula!

Playdough activity: Modeling Fertilization to the gastrula stage of development. Foldable: The teacher will provide you with a template. Create a foldable to show the process of fertilization to the gastrula stage.

Tissue Development Open textbook to page 697. Look at figure 6. Endoderm: the inner layer of cells in the gastrula. Endoderm cells develop into the digestive organs and the lining of the digestive tract. Ectoderm: the outer layer of cells in the gastrula. Ectoderm cells develop into the nervous tissue and skin. Mesoderm: the layer between the ectoderm and endoderm. Only found in some animals Mesoderm cells become muscle tissue, the circulatory system, the excretory system, and in some species, the respiratory system.

End of Section 1 Turn to page 697 and complete the Section 1 Assessment Questions 1-4. We will do number 5 as a class! Turn it into the basket before you leave! This will be a classwork grade.

Section 2 Vocabulary Symmetry Radial Symmetry Bilateral Symmetry Asymmetry Anterior Posterior Cephalization Dorsal Ventral Coelomate Pseudocoelomate Acoelomate Protostome Deuterostome

Animal Body Plans Animal phylogeny can be determined, in part, by body plans and the way animals develop. Phylogeny: evolutionary history of a species Anatomical features in animal body plans produce the tree’s branches.

Evolutionary Tree Open book to page 699. Which group of organisms is most closely related to phylum Arthropoda? Summarize the structure of an evolutionary tree. How is time shown in the evolutionary tree? What do the branches of the tree represent? Which animal evolved first? How about the most recent? Which groups have a pseudocoelom? What do echinoderms and chordates have in common?

Development of Tissues As animals evolved from the first multicellular forms, the first major change in body plans was indicated by the presence of tissues. (1st branching of the evolutionary tree) The only animals without tissues are sponges.

Symmetry The 2nd branching on the evolutionary tree is symmetry. Symmetry: describes the similarity or balance among body structures of organisms. Body symmetry enables animals to move in certain ways.

Asymmetry Asymmetry means the animal exhibits no symmetry. The animal’s shape is irregular. Example: Yellow Tube sponge

Radial Symmetry An animal with radial symmetry can be divided along any plane through a central axis. The animal will be divided into roughly equal halves. Example: Atlantic Sea Nettle Jellyfish and most other animals with radial symmetry develop from the ectoderm and endoderm

Bilateral Symmetry Bilateral Symmetry: The animal can only be divided into mirror image halves along ONE plane. Example: Humans and birds All animals with bilateral symmetry develop from 3 embryonic layers: Ectoderm, Mesoderm, and Endoderm.

Cephalization Bilateral animals have an anterior and posterior end. This body plan is known as cephalization. Cephalization: the tendency to concentrate nervous tissue and sensory organs at the anterior end of the animal. Most animals with this body plan move through environments with the anterior end first. Also, animals with this body plan have dorsal and ventral surfaces.

Body Cavities The third branch on the evolutionary tree is body cavities. Turn to page 701. Distribute Coelomate handout.

Coelomates Have a coelom Example: Humans, insects, fishes Coelom: fluid filled body cavity completely surrounded by mesoderm Key adaptation for development of larger and more specialized body structures. Specialized organs and systems that formed from the mesoderm developed in the coelom. Muscle tissue, circulatory system, excretory system, and in some the respiratory system

Pseudocoelomates Pseudocoelom: fluid filled cavity that develops between the endoderm and mesoderm. Lined partially with mesoderm Tissue, organ, and system development is limited! Example: Roundworms

Acoelomates Do NOT have the fluid filled cavity (coelom) between the gut and body wall. Body plan is still derived from endoderm, mesoderm, and ectoderm. Nutrients and wastes diffuse from cell to cell. Do not have a circulatory system Example: Flatworm

Coelomate Development From the evolutionary tree, we can observe that protostomes and deuterostomes are branches of coelomate animals. Biologists are able to identify closely related animals based on their patterns of embryonic development.

Coelomate Development: Protostomes The mouth develops in the 1st opening of the gastrula; anus develops from the 2nd opening. The anus is at the top of the gastrula while the mouth is at the bottom. As development continues, the final outcome of each cell in the embryo can NOT be changed. If one cell is deleted, the embryo will NOT develop into a normal larva. At the 8 cell stage, the top 4 cells are NOT aligned with the bottom 4 cells. Gives a spiral shape The mesoderm splits down the middle and the cavity between becomes the coelom.

Examples of Protostomes Mollusks Annelids Arthropods

Coelomate Development: Deuterostomes The anus develops in the 1st opening of the gastrula; mouth develops from the 2nd opening. The mouth is at the top of the gastrula while the anus is at the bottom. As development continues, the final outcome of cells can be changed. A cell in the early embryo, if removed, is able to form a new embryo. During the 8 cell stage, the top 4 cells and the bottom 4 cells are neatly aligned with each other. Gives radial shape As development continues, the coelom forms from 2 pouches.

Examples of Deutrostomes Echinoderms and Chordates

Segmentation The last branch of the evolutionary tree is segmentation. Example: Scorpion (Annelids, Arthropods, and Chordates) Segmentation is important because if damage occurs to one segment, another segment more than likely is able to perform the damaged segment’s function. Segments can move independently. Flexibly increased Movements are more complex

End of Section 2 Open textbook to page 704. Complete the section 2 assessment questions 1-4 and 6. Place in the basket before you leave! Classwork grade.