Transcript Animals
Animals What is an animal? • Multicellular, eukaryotic, heterotrophic, nonphotosynthetic, without cell walls • Either vertebrates or invertebrates • Containing specialized cells that have a division of labor in a organism. Animals have specialized cells to enable them to sense and seek out food and mates, and allow them to identify and protect themselves from predators. Seven Survival Methods • Feeding - herbivores, carnivores, parasites, filter feeders, detrivores • Respiration-exchange of gases • Internal transport - circulatory system; open or closed • Excretion - removal of waste • Response - use of nerve cells to respond • Movement-use of muscles & skeleton • Reproduction-sexual or asexual;live young or eggs Stages of Development • Most animals develop from a fertilized egg cell called a zygote. In animals, fertilization may be internal (inside the body) or external (outside the body). • After fertilization, the zygote of different animal species all have similar, genetically determined stages of development. • Fertilization occurs when a sperm cell penetrates the egg cell, forming a new cell called a zygote. • The zygote divides by mitosis and cell division to form two cells in a process called cleavage. • Once cell division has begun, the organism is known as an embryo. • First layer – blastula, second layer – gastrula – Endoderm – inner lining – Ectoderm – outer lining – Mesoderm – middle lining What is symmetry? • To have a consistent overall pattern of structure. • Three types – Radial - similar parts that branch out in all directions from a central line – Bilateral - two similar halves on either side of a central line – Asymmetrical – having no symmetry What are the body regions? • Based on normal orientation of the organism. – – – – Anterior - head region Posterior - tail region Dorsal - top or back region Ventral - bottom or stomach region What is cephalization? • The gathering of sensory organs and brain structures in the anterior region. • Organisms with cephalization will always have bilateral symmetry. Animal Protection & Support • Exoskeleton – hard outer covering made of chitin. • Endoskeleton – made of calcium carbonate, cartilage or bone. • Invertebrate – animals without backbones but w/exoskeletons • Vertebrate – animals with backbones. Kingdom Animalia Phylum Porifera Sponges Sponges • No mouth, stomach or other organs • sessile -(not moving) as adults, mobile -early stage • no symmetry • smallest - 1 cm long • largest - 2 m wide • filter feeders • reproduce both ways • hermaphrodites - containing both sexes Parts of the sponge • Epithelia-like cells – thin and flat responding to touch. • Collar cells – lining the interior of the sponge. Each cell has a flagellum used to draw water into sponge. • Pore cells – surrounds each pore that allow water to carry food and oxygen into the body. • Osculum- large opening where water and waste is pumped out. • Spicules - hard particles made of CaCO3 or SiO2 used for support. • Amebocytes- b/t the two layers that aid in bringing in food, reproduction and making spicules. Kingdom Animalia Phylum Cnidaria Hydra, Jellyfish, Coral What are the body shapes & parts? • Two body shapes – polyp - specialized sessile shape – medusa - specialized bell shape for swimming • Parts – epidermis - outer layer – mesoglea - middle layer – gastrodermis - “stomach skin” inner layer More Parts • Gastrovascular cavity - the “stomach” or hollow gut surrounded by tentacles. • The tentacles contain nematocysts which are stinging structures used for defense and capturing food. • This group is considered to be carnivores with radial symmetry. • Both sexual and asexual reproduction • Simple nervous system w/out a brain using a nerve net to conduct impulses. Classes of Cnidarians • Class Hydrozoa – hydras and siphonophores • Mostly marine polyp colonies • reproduce both ways • Hermaphrodites • examples include: – Obelia, Portuguese man-ofwar Photo credited by key-biscayne.com Eleutheria dichotoma Ectopleura larynx Gonothyraea loveni Class Scyphozoa • • • • Jellyfish Medusa is dominant stage Everywhere in oceans Only class of totally venomous organisms • Most are harmless but some can cause death. • Examples: Australian box jellyfish, moon jellyfish, Lion mane jellyfish Body plans of the Scyphozoans Class Anthozoa • Sea anemones & corals. • Polyps is the only form and they feed on passing prey. • Corals are made of calcium carbonate live in shallow depths make coral reefs. • Tropical and Subtropical waters Class Ctenophora • “Comb jellies” • Beat cilia to move • Secrete sticky mucus to attack prey • Most are hermaphroditic • Unique feature bioluminescent All Material Copyright: © Wim van Egmond Kingdom Animalia Phylum Platyhelminthes Flatworms Flatworm Make-up • Simplest animal with bilateral symmetry exhibiting cephalization • Range from 1 mm to several meters • Found in marine, freshwater & moist land habitats • No circulatory or respiratory system • One opening for food in and out • Contain a gastrovascular cavity • Eyespots – used to sense intensity & direction of light • Pharynx – used to ingest food • Flame cells – collects excess water & removes it • Proglottids – body sections: old ones near Class Turbellaria • Mostly free-living marine • Move by swimming w/a wave-like motion or a mucus and cilia • Feed as scavengers, carnivores • Reproduction – sexually as hermaphrodites that fertilize each other internally and asexually through regeneration. • Contain eyespots, pharynx, flame cells & simplistic nervous system with ganglia. • Most common type is the planarian “cross-eyed” Marine Flatworms Pictures of Planarians “Cross-eyed” worm Class Cestoda • Tapeworms – humans house seven different species. Lives in the intestines as parasites • Contains a scolex “head” with suckers & hooks for attaching & proglottids which have muscles, nerve cells, & reproductive cells. Each proglottid can contain 100,000 eggs. • No eyespots, mouth, gastrovascular cavity, or digestive organs. • Almost all are hermaphroditic. • Can grow up to 10 m or 33 ft long. • Beef, pork and other types. Beef Tapeworms Life cycle - eggs left behind by infected organism. Ingested by cow(intermediate), cow slaughtered, people eat undercooked meat, eggs hatch and infect human (primary), eggs exit in feces. http://www.merck.com Class Trematoda • Parasitic & hermaphroditic • Blood flukeSchistosoma – causes schistosomiasis. See life cycle on Pg. 710 • Brown fluke – N. America causes swimmer’s itch • Liver fluke Phylum Nematoda • • • • • Roundworms Digestive tract w/two openings Most are separate sexes Protective layer - cuticle Most free-living, some parasitic living in soil, animals, fresh and salt water. • Humans play host to 50 types Types of Roundworms • Ascaris - intestines of pigs, horses, humans. • Lay about 200,000 eggs • Hookworms - burrow into foot through blood to the intestine. 400 million people infected worldwide. Types of Roundworms • Trichinella - causes trichinosis. Humans, pigs, mammals. Eating undercooked pork. • Pinworms - most common in US • Filarial worms -tropical countries. Causes elephantiasis Pinworm Original image from Oklahoma State University, College of Veterinary Medicine.) Phylum Rotifera • Rotifers • transparent, freeliving, fresh water • uses flame cells • bilateral symmetry w/cephalization • two eyespots all material © Wim van Egmond