Presentation on theme: "Introduction to Animals"— Presentation transcript:
1Introduction to Animals Chapter 26Introduction to Animals
2Characteristics of Animals There are 3 general features of animals which all animals share:All animals are multicellular.All animals are heterotrophs.All animal cells lack cell walls.
3Characteristics of Animals Another feature most animals share is that they are mobile.Certain animals, however, such as sponges and corals are immobile.
4Two Main Classes of Animals Animals fall into one of two categories:Invertebrates-animals that lack a backbone.The vast majority of animals are invertebrates.SpongesAntsSquidVertebrates-animals with a backbone.Cats, Dogs, BirdsFish, Frogs, TurtlesHumans
5InvertebratesOn land, these are usually very small because they do not have an internal skeleton for support.They assist with the pollination of plants and the decomposition and recycling of dead material in an ecosystem.
6VertebratesVertebrates have a cranium and an internal skeleton composed of bone or cartilage.Their vertebra protect the nerve cord and provide a site for muscle attachment.
7Animal Body SystemsAn animal’s skeleton provides a framework that supports the animal’s body.There are three main types:Hydrostatic-a water filled cavity under pressure.Think jellyfish.
8Animal Body SystemsExoskeleton-a rigid external skeleton encasing the body of the animal.Think lobsters.
9Animal Body Systems Endoskeleton-a rigid internal skeleton. Think humans.
10Digestive and Excretory Systems The digestive system extracts energy and nutrients from an animal’s food.Some animals have a gastrovascular cavity with a single opening allowing food in and out.Other animals have a one-way digestive tract with two openings. The food moves in through the mouth, and out through the anus.
11Digestive and Excretory Systems The excretory system removes wastes from the animal’s body.Most of these wastes are produced as a result of cellular metabolism.Ammonia is a main waste that needs to be removed.Animals have to remove waste products and maintain an internal osmotic balance.
12Nervous SystemsThe nervous system carries information about the environment through the body and coordinates a response.There are two main types:SimpleComplex
13Simple Nervous Systems Nerve nets have no complex arrangement. There is no coordinated response to stimuli.Jellyfish and hydras.
14Simple Nervous Systems Other animals have clusters of nerve cells called ganglia which can coordinate responses to stimuli.Flatworms.
15Complex Nervous Systems These animals have true brains with sensory structures.These animals can have high level interactions with their surroundings.Grasshoppers, humans, dolphins.
16Respiratory SystemsThis system is responsible for exchanging O2 and CO2 between the organisms and the environment.Some animals have gills that allow for gas exchange in the water.Other animals have lungs that allow for exchange on land.
17Circulatory SystemThis system transports gases, nutrients, and other substances within the body.Open circulatory systems-have a heart that pumps the O2/nutrient rich fluid through the body to feed the tissues and cells.Closed circulatory systems-have a heart that pumps blood through a system of vessels.
18Reproduction Reproduction is important for the survival of a species. There are two main strategies:AsexualSexualEach one has unique advantages and disadvantages.
19Asexual Reproduction Advantages Disadvantages No need to find a mate. Little, if any, genetic diversityOne disease/illness could potentially wipe out a species.
20Sexual Reproduction Advantages Disadvantages High variety within the genome.Not as susceptible to disease.DisadvantagesNeed to find a mate.
21Body PlansAnimals body plans describe the animal’s shape, symmetry, and internal organization.The cells of all animals except sponges are arranged into units called tissues.Tissues are groups of cells that carry out a specific function.Tissues are often organized into organs which perform specific jobs.
22Body SymmetryBody symmetry describes how an animal’s body can be divided into similar pieces.Asymmetry describes an animal that cannot be divided into similar pieces.Radial symmetry describes animals whose symmetry revolves around a central axis.Bilateral symmetry describes an animal that has right and left sides which are mirror images of each other.
23Embryonic Development The diploid zygote is the first stage of the new individual.Cell division makes up the second stage of development. The zygote does not increase in size.
24Embryonic Development Eventually a blastula, which is a hollow ball of cells is formed.
25Embryonic Development After the blastula has formed, one side of the organism begins to pinch inward to form the gastrula.The structure is called the blastopore.
26Developmental Patterns Eventually the blastopore reaches the other side of the organism and a second opening forms.In protostomes, the first opening becomes the mouth.Clams, snails, earthworms, insectsIn deuterostomes, the first opening becomes the anus.Sea stars and vertebrates
27Cell DifferentiationDuring gastrulation, the cells of the gastrula begin increasingly different from one another.
28Cell DifferentiationThis leads to the formation of the three main tissue types:Endoderm-forms the gut, respiratory system, many glands.Mesoderm-forms most of skeleton and muscles, circulatory system, excretory organs.Ectoderm-outer layer forms the skin, nervous system.
29Body CavitiesOnce the tissue layers start to form and development continues, body cavities start to form.
30Body Cavities A coelomate has a body cavity surrounded by mesoderm. A pseudocoelomate has a body cavity, but it is not lined by mesoderm.An acoelomate has no body cavity.
31Characteristics of Chordates At some point during development, all chordates have a dorsal nerve cord, a notochord, pharyngeal pouches, and a post anal tail.
32Characteristics of Chordates Most chordates are vertebrates.Tunicates and lancets are invertebrate chordates and represent an evolutionary link between vertebrates and invertebrates.
33The First VertebratesThe first vertebrates evolved about 500 million years ago.They were essentially a fish-like animal with a cartilaginous skeleton rather than a bony skeleton.Very primitive and they lacked many of the features we think of today when we think of vertebrates--backbones and jaws.
34Fish EvolutionTwo features evolved in fish that set them apart from the early vertebrates: Jaws and paired fins.These fish also had hardened spines.The jaws allowed for grasping prey.Fins allowed for fast swimming in pursuit of prey.These fish were replaced by sharks and bony fishes.
35Fish Are… The most primitive vertebrates. Share the following key characteristics:They have endoskeletons, gills, closed-loop circulation, and kidneys.They also have swim bladders, fins, and lateral lines.Animals that gave rise to amphibians.
36Amphibian EvolutionEarly amphibians were poor swimmers and were not like frogs and toads of today.As competition from predators increased, the numbers of species and the diversity of amphibians increased.
37Amphibian EvolutionThere are three characteristics that helped amphibians succeed on land:Lungs-enabled the exchange of gases out of the water.Heart-a more efficient way of delivering O2 to the body than a fishes heart.Strong limbs-easy movement from place to place.Amphibians need to keep their skin and eggs moist. They live in and around water.
38Amphibians Are… The first vertebrates to live on land. They contain legs, lungs, double-loop circulation, a partially divided heart, and cutaneous respiration.They are tied to the water for reproductive purposes.Animals that gave rise to reptiles.
39Evolution of ReptilesTo make the complete move to land, vertebrates needed adaptations to allow them to do so.The watertight amniotic egg was an adaptation that allowed reptiles to move away from the water.An amniotic egg contains yolk and a shell.
40Evolution of ReptilesThe first reptiles have two important evolutionary adaptations:Watertight, scale covered skin.Amniotic egg.These adaptations allow reptiles to deal with dry conditions.The first reptiles were small dinosaurs that evolved from amphibians.
41Reptiles Are…Reptiles are animals with scales, clawed toes, and ectothermic metabolism.Reptiles lack hair or feathers.Dinosaurs were reptiles.Snakes, crocodiles, turtles, turata and lizards are examples of reptiles.Animals that gave rise to birds and mammals (from therapsids).
42Evolution of Birds Birds evolved from meat eating dinosaurs. They had skeletons that were very much like dinosaurs.The Archaeopteryx fossil (about the size of a crow) represents an intermediate form of a bird between the dinosaurs and modern birds.
43Archaeopteryx Had long teeth, arms with fingers and claws. It lacked a breastbone to anchor flight muscles.It had solid bones instead of hollow ones.It had feathers on its wings and a tail, a wishbone (fused collarbone).
44Birds Are…Animals that lay amniotic eggs, have scales that cover their legs and feet, have feathers, endothermic metabolism, a beak, a lightweight skeleton, and lungs with air sacs.
45Evolution of MammalsEarly mammals were about the size of mice, kept down by the dinosaurs.After the dinosaurs and other large marine reptiles died out, mammals increased in size, took to the oceans and came to be the dominant life forms of today.
46Mammals There are three types of mammals: Monotremes - lay eggs which quickly hatch.Marsupials - give birth to live young that crawl into a pouch to complete their development.Placental Mammals - give birth to live young that may or may not require extended care.All three reproduce by internal fertilization.
47Mammals Are…Animals that evolved from mammal-like reptiles called therapsids.Have an endothermic metabolism, mammary glands, specialized teeth, body hair.