Kingdom Animalia Animal Characteristics Animals are the most

Kingdom Animalia

Animal Characteristics • Animals are the most physically diverse kingdom but share common characteristics. • Most animals reproduce sexually.

Animal cells are supported by collagen. – three-stranded protein – found in bone, skin, ligaments, fingernails, and hair

Most animals have Hox genes • Homeotic genes control early development. – Hox genes determine the position of cells’ differentiation. – A Hox gene mutation leads to the development of a body structure in the wrong position. head tail fruit fly genes human HOX-B genes head Hox genes tell embryonic cells which body part to become. tail Mutations in Hox genes led to the vast diversity of animal species.

How are animals grouped into phyla? • Three criteria are used to categorize animals. – Body plan symmetry – Tissue layers – Developmental patterns

Body plan symmetry Asymmetry (no symmetry) Bilateral (left/right) Radial (circular, around a central axis)

• Animals are divided into two major groups, the protostomes and the deuterostomes. – Protostomes form the mouth end of the digestive tract first and the anus second. – Deuterostomes form the anus end of the digestive tract first and then the mouth.

A comparison of structure and genetics reveals the evolutionary history of animals. • Protostomes and deuterostomes are the two major radiations on the animal phylogenetic tree. NO TISSUES RADIAL lancelets, vertebrates sea stars, sea urchins crustaceans, insects, spiders Echinodermata Nematoda Arthropoda Chordata roundworms clams, snails, octopuses Segmented worms flatworms Cnidaria Platyhelminthes Annelida Mollusca jellyfish, coral, anemones sponges Porifera DEUTEROSTOMES PROTOSTOMES

• Cells are differentiated into tissues during development in all animals except sponges – Cnidarians only have 2 layers • Ectoderm (becomes skin and nerves) • Endoderm (becomes digestive tract) – All other animals have three layers • Ectoderm and endoderm • Mesoderm (becomes skeleton, muscles, organs)

• In all except sponges and cnidarians, a body cavity may develop • Having a body cavity is an advantage, as it allows for more internal space Gut Flatworms Roundworms All others

Animal Orientation dorsal anterior posterior ventral

Phylum Porifera Sponges

Sponges are asymmetrical filter-feeders

Sponges are hermaphrodites. They are able to produce both egg & sperm cells. But they DO NOT self-fertilize.

Phylum Cnidaria Jellyfish Hydra Sea Anemones and Coral

cnidocyte or nematocyst

Cnidarians are NOT hermaphrodites. They have separate males & females. They have external fertilization.

Jellyfish

Hydra are much smaller than jellyfish (almost microscopic). They use their stinging tentacles to catch protozoans.

Sea anemones

Coral live in colonies that secrete a calcium “shell” for protection (reefs)

Phylum Platyhelminthes “Flatworms” Planaria Tapeworms Flukes

§ Acoelomate § Protostome development § Cephalization § Bilateral symmetry § Two-way gut

Planaria live in freshwater or in soil. Very small and have eye spots to sense light changes.

Tapeworms and flukes are entirely parasitic. They typically live as larvae in one host and as adults in another host.

Phylum Nematoda “Roundworms”

• Pseudocoelomate • Thickened exterior cuticle • One-way gut

Many live in the soil and freshwater. Most are parasitic.

Phylum Annelida “Segmented Worms” Earthworms Leeches Ragworms

§True coelomates § 5 beating hearts– closed circulatory system §Setae—bristles (for anchoring & traction)

Earthworms (terrestrial) Leeches (mostly freshwater) Ragworms (marine)

Earthworms are hermaphrodites– but remember, they do NOT self-fertilize. They fertilize each other. The clitellum becomes a cocoon for the eggs.

Phylum Mollusca “Soft-bodied Animals” Clams, mussels, oysters Snails and slugs Octopus and squid

• Many have shells (“valves”) • Three-part body plan: head, visceral mass, muscular foot • Mucus-covered mantle • Gills • Contains smartest group of invertebrates

Bivalves

Gastropods

Cephalopods

Phylum Echinodermata “Spiny-skinned Animals” Sea Lilies Seastars and Brittlestars Sea Urchins and Sea Cucumbers

• Deuterostome development • Five-part radial symmetry • Water-vascular system • Endoskeleton

Sea Lilies (sessile) Seastars and Brittlestars

Sea Urchins Sea Cucumbers

Phylum Arthropoda Myriapods Crustaceans Arachnids Insects

Trilobites (ancient/extinct) Chelicerates (arachnids, horseshoe crabs) Myriapods (millipedes, centipedes) Crustaceans (barnacles, lobsters, crabs) Hexapods (insects)

• Chitinous exoskeleton which is shed (molted) during growth • Jointed appendages

Centipedes Mostly harmless Carnivores– eat insects, grubs, other centipedes 1 pair of legs per segment

Millipedes Herbivores Eat decaying material or plant material Some secrete poisonous chemicals through their skin as a defense 2 pairs of legs per segment

Crustaceans 2 or 3 -part body (head-thorax-abdomen) 2 pairs of antennae Biramous appendages Up to 5 pairs of walking legs

Chelicerates 2 -part body (cephalothorax and abdomen) 6 pairs of appendages 1 st pair often modified into fangs 2 nd pair modified to sense or grab (claws) 4 pairs of walking legs No antennae

Black Widow more aggressive neurotoxin Brown Recluse less aggressive necrotoxin

Insects 3 body segments 3 pairs of walking legs Up to 2 pairs of wings 1 pair of antennae

Incomplete metamorphosis • Grasshoppers • Dragonflies • Mayflies No larva is formed. Complete metamorphosis • Butterflies • Bees/wasps/ants • Caddisflies • Mosquitoes

A Butterfly comes from a chrysalis—thin, membranous. Moths usually come from fluffy cottony cocoons.

Phylum Chordata Tunicates Lancelets Vertebrates

All chordates have (for at least part of the life cycle)… • • • Notochord (stiff rod of cartilage) spine Hollow dorsal nerve cord spinal cord Pharyngeal slits gills Post-anal tail Endostyle

Tunicates -- “sea squirts” Lancelets -- “sea squirts” • Adults are sessile filter feeders • Larvae have typical chordate features • Adults are burrowing filter feeders that show primitive chordate features

Subphylum Vertebrata • Built along the basic chordate body plan • Defining characteristic is the vertebral column – Notochord segmentation + stiffness • Gills appear in all, lost in advanced forms • Highly developed dorsal nervous system – Invertebrates have ventral nervous system

Subphylum Vertebrata Class Agnatha – “jawless fishes” Class Chondrichthyes – “cartilaginous fishes” Class Osteichthyes – “bony fishes” Class Amphibia – amphibians Class Reptilia – reptiles Class Aves – birds Class Mammalia – mammals

Jawless Fishes • No paired appendages • Sharp teeth in open mouth • Exclusively aquatic hagfish lamprey Covered in copious amounts of slime

Cartilaginous Fishes • • Jawed Cartilage skeletons (no ribs) Paired fins Skin with “teeth” Unprotected gills Upper movable jaw Several rows of teeth Internal fertilization (oviparity or ovoviviparity) sharks chimaeras skates and rays

Bony Fishes • • • Bone skeletons (no ribs) Skin with scales Swim bladders Gills protected External fertilization (ovuliparity)

Amphibians • Metamorphosis from aquatic larva with gills to terrestrial tetrapod with lungs • Require water for external fertilization (ovuliparity) • Evolved from lobe-finned fish • Separate pulmonary and systemic circulation salamanders and newts caecilians -legless sirens -external gills frogs and toads

Pulmonary refers to the lungs. Amphibians (as well as other vertebrates) have a separate circulatory circuit to the lungs.

Reptiles • No aquatic larval stage, only tetrapodal adult • Dry, watertight skin • Internal fertilization (oviparity or ovoviviparity) turtles, terrapins and tortoises • Amniotic egg allows reproduction on land tuatara lizards and snakes crocodilians

Birds • • • Endothermic Feathers Upper limbs modified into wings Toothless beak Amniotic egg with hard, oblong shell Internal fertilization (oviparity) Hollow bones Evolved from reptiles Heart chambers complete separate oxygenated-deoxygenated blood

In fish & amphibians – kidneys are adapted to rid excess water In reptiles & birds – adapted to conserve as much water as possible In mammals – kidneys are adapted to maintain water balance

Mammals • • Hair Mammary glands Middle ear bones Internal fertilization (oviparity or viviparity) • Evolved from reptiles Marsupials -Born undeveloped -Further development occurs in pouch -Kangaroo, opossum, koala Monotremes -Lay eggs -No nipples -Echidna and platypus Placentals -Born fully developed -Young attached within via placenta to receive nutrients