3.4: The Animal Kingdom pg Eukaryotic, multi-cellular organisms, and do not have cell walls.

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1 3.4: The Animal Kingdom pg. 111 The kingdom of animalia contains 35 different phyla. Reptiles, birds and fish only represent a single phyla. 95 % of the remaining animals are found in the other 34 phyla. The largest number of animals ( ) are found in the Phylum Arthropoda. What is an Animal? Animals have the following characteristics; - Eukaryotic, multi-cellular organisms, and do not have cell walls. - They are heterotrophs, which ingest and digest their food. - Mobile, or have the ability to move, in at least one stage of their lives. - Reproduction is sexual, producing an embryo that undergoes stages of development. Characteristics used to Classify Animals Invertebrate: an animal that does not have a backbone. Vertebrate: an animal with an internal skeleton and a backbone. Animals can be classified by whether they have a backbone or not. 95% of animals are invertebrates, other characteristics used to classify animals are; - Levels of organization - Segmentation - Number of body layers - Movement - Symmetry and body plans - Reproduction - Body cavity

2 Figure 3.23: About 95 percent of animals are invertebrates. (A) Sponges live in aquatic environments, attached to solid surfaces such as rocks, coral, or the shell of another animal. (B) Sea anemones use their stinging tentacles to catch food. (C) Sea cucumbers feed on dead and decaying matter. Levels of Organization Animals are classified by looking at their structure, tissue, and organ systems. All animals have cells organized into tissues, except for sponges. Cells tissues organs organ systems organism Number of Body Layers All animals express three body layers, except for sponges and cnidarian (hydras and jellyfish). These layers are: ectoderm (skin, nerve tissue and some organs), mesoderm (muscles, blood, kidneys and the reproductive organs), and endoderm (lungs, liver, pancreas, bladder, and the stomach lining). These layers are developed during embryo development. Figure 3.24: Most animals develop three layers of cells at an early stage in the growth of the embryo.

3 Symmetry and Body Plans Asymmetrical body plan: organisms have an irregular shaped body plan; for example, the sponge. Radial symmetry: a body plan that can be divided along any plane through a central axis, into roughly equal halves. (Hydra, jellyfish, and starfish) Bilateral symmetry: a body plan that can be divided along one plane, through the central axis, into equal halves. (Worms, insects and vertebrates) Figure 3.25: (A) the cnidarian that is known as a hydra shows radial symmetry. (B) The turtle shows bilateral symmetry. Body Cavities Coelom: a fluid filled body cavity that provides space for the development and suspension of organs and organ systems. Coelomates: are organisms that have a coelom. (Worms. mollusks, insects and vertebrates) Acoelomates: are organisms that do not have a fluid filled space. (coral, jellyfish and flatworms) Figure 3.26: (A) Acoelomate animals have flattened bodies. (B) Coelomate animals have a body cavity in which complex internal organs can develop.

4 Segmentation Segmentation is the division of the body into repetitive sections, or segments. The advantage to segments, is if a segment gets damaged the other segments are unaffected. Segments also allow for greater mobility and complex patterns of movement of the organism. Movement As organisms evolved, nerve and muscle tissue developed in organisms. This allowed for complex and fast movements. Some organisms are sessile as adults, sponges and anemones. Reproduction Most animals reproduce sexually, using gametes (haploid), fertilizations leads to the development of a zygote (diploid). Fertilization can either be external or internal. Invertebrate Animals Invertebrates are aquatic and terrestrial organisms, found in most ecosystems on Earth. The organisms have existed for hundreds of millions of years. Sponges and Cnidarians Phylum Porifera are found in both marine and freshwater environments. They have an asymmetrical body plan and no tissues. The sponges are only two layers of cells, with each cell living independently of each other. The sponge is a sessile organism when it reaches adulthood. They feed by passing water through channels and trapping food particles.

5 Phylum Cnidaria marine and freshwater organisms; such as, a Hydra, Jellyfish, Anemones and Coral. These organisms are also made up of only two layers of cells, yet they have tissues. They have muscle tissue to allow movement, and a nerve network to coordinate these movements (to capture prey and swim). They have a digestive system, one opening, two directional. Sting tentacles capture the prey and deliver it to the mouth, where the prey enters the gastro-vascular cavity for digestion. Cnidarians express a radial symmetrical body plan. Figure 3.28: (A) Sponges are animals that have no tissues, no organs, and an asymmetrical body plan. (B) Corals are cnidarians that can form reef environments. Two Body Forms Polyp: the tube-shaped sessile body form of cnidarian. Medusa: the umbrella-shaped, free swimming body form of cnidarian. Figure 3.29: There are two basic forms of cnidarians: polyps and medusae. (A) Polyps, such as adult sea anemones, are sessile. (B) Medusae, like the jellyfish shown in the photo, are mobile.

6 Worms Phylum Platehelminthes: (flatworms) are Acoelomates that have three layers of cells. They express a simple nervous system, a gathering of nerve cells creating an eye spot, a simple brain at a head region. (Tapeworms, flukes, and free-living planarians) Cephalization: the concentration of nerve tissue and receptors at the anterior end of an animal s body. Phylum Nematoda: round worms (hookworm, pinworm and vinegar eel) that live in all habitats, and can be free-living or parasitic. Cylindrical and tapered ate one end. Phylum Annelida: segmented worm, are long tube-like organisms that are divided into a series of ringed segments. These worms have a distinct head region with a brain and a number of organ systems (digestive, circulatory, nervous, excretory, and reproductive). The digestive system is a two opening (mouth and anus) and one directional. Figure 3.31: Segmented worms, like this earthworm, are coelomates that are segmented on the inside as well as on the outside.

7 Mollusks Phylum Mollusca: there are over species, making them the second most diverse animal phylum. They express bilateral symmetry. Mollusks have a soft body plan surrounded by a hard shell. Mantle: a membrane that surrounds a mollusk s internal organs. The mantle creates a calcium carbonate shell, protecting organ systems; such as, digestive, circulatory, respiratory, excretory, reproductive and nervous). The octopus has a relatively large brain, and is capable of learning complex tasks. Figure 3.32: Three of the major classes of mollusks are (A) the bivalves, represented here by a file clam; (B) the gastropods, represented by a land snail; and (C) the cephalopods, represented by an octopus. Echinoderm Phylum Echinodermata: made up of sea stars, sea urchins, sea cucumbers and sand dollars. These organisms express radial symmetry, spiny endoskeletons (internal skeleton), and tube feet (fluid-filled, similar to suction cups). Arthropods Phylum Arthropoda: is the largest animal phylum. (Spiders, scorpions, crustaceans [lobsters], and insects) They have moveable jointed legs and body segmentation. These organisms have an exoskeleton.

8 Exoskeleton: is an external skeleton that protects organs, provides support for muscle attachments, and protects against water loss and predation. Table 3.5: Characteristics of Arthropod Groups Vertebrate Animals Phylum Chordata: ( species) Most chordates are vertebrates, have a notochord which eventually develops into a spine, brain and spinal cord. Notochord: a flexible, rod-shaped structure found in chordate animals; during vertebrate development it is replaced by the spine. Cartilage: the flexible, non-bony tough material found in vertebrate endoskeletons.

9 Fish (half of all vertebrates are fish, developed 400 million years ago) Found in fresh water and saltwater habitats. The lamprey is the oldest living vertebrate. Jaw less fish, uses suction mouth to latch onto their food. Cartilage endoskeleton Fish use gills to obtain oxygen from the water. Bony fish have an air sac that allows them to rise and sink in the water, called a swim bladder. Figure 3.35: (A) the sea lamprey is thought to be the most ancient of all living vertebrates. It is jawless and has a cartilaginous skeleton. This species uses its mouth to hold on to and penetrate the bodies of prey. (B) The cartilaginous fish include the sharks and rays, like this manta. (C) The bony fish include the vast majority of the Earth s current fish diversity, such as Ontario s pumpkinseed sunfish. Amphibians (360 million years ago) (frogs, toads, and salamanders) The first limbs were modified fins. They have lungs, and also use their skin to gas exchange, and reproduce externally. Figure 3.36: In Ontario, there are representatives of the two major amphibian orders. The bullfrog (A) is an anuran (frogs and toads), and the spotted salamander (B) is a urodelan (salamanders and newts).

10 Reptiles (300 million years ago) There are four major groups (three orders): lizard and snakes, turtles, crocodilians. Reptiles have a three chambered heart, share the ventricle. These animals are ectothermic. Ectothermy: the reliance on the environmental heat for determining internal body temperature. Use lungs for gas exchange. Reproduction is done by internal fertilization, and they lay shelled eggs on land. (amniotic egg) The incubation temperature will determine the sex of the offspring. Figure 3.37: In the three orders, the four major groups of living reptiles are the snakes, lizards, turtles, and crocodilians. The eastern foxsnake (A), five-lined skink (B), and wood turtle (C) are all Ontario residents. The gavial (D) is an endangered species on the Indian subcontinent. Birds (150 million years ago) (Related to at least one group to dinosaurs) Birds are edothermic and have a four chambered heart. Endothermy: the use of metabolic heat to maintain a high, constant body temperature. Bones are light weight and hollow, and adaptation for flying, a toothless skull (beak) and a compact body plan for weight reduction.

11 Figure 3.39: (A) Black-capped chickadees are small songbirds whose range covers parts of Canada and the United States. (B) Ostriches are large birds that do not fly. They live in desert and grassland regions of Africa. Mammals Females have mammary glands that produce and secrete milk to nourish developing young. Mammals also have hair that has multiple functions, defense, sensory detection, waterproofing communication, insulation and camouflage. Mammals are endothermic animals, with a four chambered heart, highly developed brains. There are three main groups; momotremes, marsupials, and placental mammals. Mammary gland: a mammalian gland that produces and secretes milk for nourishing developing young. Placenta: an organ in the pregnant uterus that exchanges nutrients and oxygen between the mother and developing offspring. See Table 3.6, page 123 for characteristics of each group.

12 Table 3.6: Characteristics of Mammal Groups Section 3.4: Review, questions 1 15, page 124