Warm-Up, Monday What is an animal? What makes an organism an animal?

Animal Development Chapter 18

What you need to know! The characteristics of animals. The stages of animal development The traits used to divide animals into groups The four chordate characteristics. Adaptations that lead to the development of mammals.

Animal Characteristics Multicellular eukaryotes Heterotrophic Obtain nutrients by ingestion (eating) Extracellular matrices hold the cells together No cell walls Nerve and muscle cells

Early Embryonic Stages Meiosis makes haploid sperm and/or egg Zygote: fertilized egg Cleavage begins (division without growth) Blastula: cells form an outer layer with a hollow inner cavity Early Gastrula: in-folding of cells forms layers Gastrula: complete layering of tissue

Early Embryonic Development

Animal Development Some animals develop directly into adults Many animals develop into a larvae (sexually immature form) that has a different niche from the adult Larvae undergo metamorphosis that transforms into an adult Most animals are invertebrates

Invertebrates

Body Plan Morphological and developmental traits that help to categorize animals Tissues Symmetry Body Cavity Protostomes or Deuterostomes

1. Tissue Tissue: Collections of specialized cells isolated by membranous layers Ectoderm Outermost layer that becomes the skin and nerve tissue Mesoderm Inner layer that becomes skeletal, muscle and blood tissue Endoderm Internal layer that becomes the digestive tissue

2. Symmetry Radial symmetry with tops and bottoms but no left/right/front/back Bilateral symmetry with front (anterior), behind (posterior), backside (dorsal), and stomach (ventral)

Body Cavity (Coelom) Fluid filled body cavity for organs, cushioning organs and/or to form a hydrostatic skeleton Pseudocoelomate: body cavity lined w/ mesoderm and endoderm True Coelom: organisms with a body cavity lined only with the mesoderm

3. Protostome or Deuterostome Protostome blastopore becomes mouth Deuterostome blastopore becomes anus

Chordate Derived Characters

Phylum Chordata Characteristics Dorsal (hollow) nerve cord Notochord – long flexible rod that appears during embryonic development (not a spinal cord!) Pharyngeal slits Muscular post-anal tail

Chordates → Mammals

Tetrapods: https://www.youtube.com/watch?v=yvDQCa7rleI Published on Feb 27, 2013 Professor Neil Shubin talks about the discovery of Tiktaalik and one of the greatest evolutionary events in Earth's history: when the very first fish ventured out onto land. Widely known as the "fishapod", Tiktaalik roseae is a 375 million year old fossil fish discovered by a team of six palaeontologists in the Canadian Arctic in 2004. Tiktaalik looks like a cross between the primitive fish it lived amongst and the first four-legged animals, a group called "tetrapods". Derived from "tetra-", meaning four, and "-pod", meaning foot, all animals that descended from these pioneer amphibians, including us, can be called tetrapods. Tiktaalik lived about 12 million years before the first tetrapods (which are approximately 363 million years old). With the earliest appearance in the fossil record of tetrapod features in a fish, the discovery has become a key piece of evidence in the transition from life in water to life on land.

Mammals to Humans Mammals: Mammary glands (milk producing glands for offspring), hair, fat layer under skin, endothermic (high metabolism) Primates: opposable thumb Humans: large brain and bipedal locomotion

Primates to Humans https://www.youtube.com/watch?v=29u6XRY51Bk

Invent an Animal-Tuesday Determine which classification the animal would fall under. What are the stages of development of the animal? Why is the organism you created an animal? Explain. Draw a picture of your animal.

Animal Classification Project You and a partner will: Create a poster for one classification of animal. On your poster, use diagrams, charts, words, etc. to explain the: Key features of your classification of animal. Why the animal is considered a vertebrate or invertebrate Development and ancestors of the animal

Classifications: Sponges Cnidarians Flatworms Nematodes Molluscs Annelids Arthropods Insects Echinoderms Chordates Lampreys Jawed vertebrates Amphibians Reptiles Birds Mammals Humans