Introduction to animals Introduction to Animals – Ch. 32

The Nature of Animals Section 32.1

Classification: ● 95-98% of animals are invertebrates ● Without a backbone ● 2-5% of animals are vertebrates ● With a backbone

Animal Traits

Characteristics: All animals are: 1. Multicellular 2. Eukaryotic 3. Ingestive heterotrophs 4. Lacking in cell walls 5. Sexually reproductive 6. Able to move

1. Multicellular Organization ● Cell specialization: the evolutionary adaptation of a cell for a particular function ● Tissue: group of similar cells that perform a common function ● Cell junctions: connections between cells that hold them together as a unit

Atom Molecule or compound Organelle CELL Levels of Organization Tissue Organ Organ system Organism Life begins

2. Eukaryotic cells

3. Ingestive Heterotrophy ● Getting complex organic compounds (carbon) from sources other than the sun ● Ingestion: taking in food usually in the form of an other organism ● Digestion: the body’s process of extracting organic molecules from food

Lions Feeding (Ingestion)

4. Lack of cell walls

5. Sexual Reproduction & Development ● Hermaphrodites: producing both eggs and sperm ● Examples: worms & sponges ● Most do NOT fertilize own eggs ● Why not? ● Zygote: diploid cell that results from the fusion of two haploid gametes ● Undergoes differentiation (cells becoming specialized to perform a specific function)

Mating and Mating Behaviors Beetles Mating Male Female Young Courtship

Leeches Exchange Sperm During Mating Mating leech

Parthenogenesis: ● Females of some animals produce eggs, but the eggs develop without being fertilized! ● New offspring will be all female ● Example animals: some fishes, several kinds of insects, and a few species of frogs and lizards

Parthenogenesis in the Komodo Dragon Video Video !

6. Movement ● Sessile: attached & non-moving ● sponges ● Sedentary: move very little ● clam ● Motile: animals that can move ● humans ● Ability to move depends upon interaction between nervous tissue and muscle tissues ● Neurons: cells of nervous tissue

SESSILESEDENTARY MOTILE Sponge Chiton Cheetah

Origin of Animals: ● Animals came about in the water ● Evolved from colonial protists: ● Each organism had its own function (for the colony) much like each cell of the animal body has its own function (for the organism) Vide o

Body Structure: ● Symmetry is the arrangement of body parts around a central plane or axis ● Asymmetry occurs when the body can’t be divided into similar sections ● sponges

Radial symmetry ● when body parts are arranged around a central point ● like spokes on a wheel ● echinoderms ● Most animals are sessile (attached) or sedentary (move very little)

Bilateral symmetry ● when animals can be divided into equal halves along a single plane ● right and left sides that are mirror images of each other ● are usually motile ● Show cephalization ● concentration of sensory organs on the head (anterior) end

What type of symmetry is this?

Segmentation ● When an animal body is composed of a series of repeating similar units ● Example: earthworm (annelid) ● Segments may look different & have different functions ● Example: insects & crustaceans (arthropods)

Anatomical Terms: Dorsal: back surface of animal Ventral: underside of animal Anterior: front end of animal Posterior: rear end of animal Lateral: sides of animal Medial: along midline of animal Proximal: near to Distal: away from

Label the parts:

Comparison of Invertebrates & Vertebrates Section 32.2

Invertebrate groups Video !

Invertebrates ● Simplest animals ● Contain the greatest number of different species ● Most are aquatic ● Do NOT have a backbone ● Includes: ● sponges, cnidarians, flatworms, roundworms, annelids, mollusks, arthropods, & echinoderms

Sponges – Phylum Porifera Osculum of Sponge

Sea Anemone – Phylum Cnidaria Tentacles of Sea Anemone

More Phylum Cnidaria * Brain Coral Red jellyfish

Flatworms – Phylum Platyhelminthes Planarian Marine Flatworm

Roundworms - Phylum Nematoda Segmented Worms – Phylum Annelida Nematode Leech (segmented worm)

Phylum Mollusca (With and Without Shells) snailscallop nautilus nudibranch octopus

Phylum Arthropoda Dung beetle Horseshoe crab crayfish spider

Phylum Echinodermata Sea cucumber Sand dollar starfish Brittle star Sea fan (crinoid)

Symmetry ● Most are radial or bilateral ● Radial can receive stimuli and move in any direction (in water) ● Some are highly cephalized Bilateral but NOT an invertebrate Radia l Bilatera l

Support of the Body ● Various types of support: 1. Simple skeletons (sponges) 2. Fluid-filled body cavity (roundworms) 3. Exoskeleton (crayfish) ● Rigid outer covering for protection of soft tissue

2 Types of Circulatory Systems: ● Open circulatory system: circulatory fluid is pumped by the heart through vessels into a body cavity ● Arthropods & most mollusks ● Closed circulatory system: circulatory fluid is restricted to vessels in a closed loop ● Squid (mollusk) V IDEO

Digestive & Excretory Systems ● Gut: a digestive tract running through the body ● Liquid wastes are excreted as ammonia ● highly toxic

Development ● Indirect Development: an intermediate larval stage occurs ● Flies ● Direct development: young animal appears similar to adult ● grasshoppers

Indirect Developme nt

Vertebrate Groups Video!

Fishes – Classes Myxini, Cephalaspidomorphi, Chondrichthyes, Actinopterygii, and Sarcopterygii lancelet ray anglerfish damselfish

Class Amphibia toad newt frog salamander

Class Reptilia Turtle Snake Alligator Lizard

Class Aves hummingbird ostrich lovebirds

Class Mammalia

Vertebrata ● More complex animals ● Most have a backbone made up of individual bones called vertebrae ● All species are in the Phylum Chordata ● From simplest to most complex groups: ● Fish ● Amphibians ● Reptiles ● Birds ● Mammals

Support of Body ● Vertebrates have endoskeletons ● Internal skeletons ● Supports more weight ● Grows as animal grows (no molting) ● Some vertebrates have skeletons of cartilage ● sharks, rays, and skates ● Other vertebrates have skeletons of bone and cartilage ● reptiles, birds, & mammals

Bone & Cartilage in Fetus

Segmentation ● Vertebrae: repeating bony units of the backbone ● Vertebrae & ribs are segmented

Body Covering ● Integument: outer covering of an animal ● Terrestrial animals are water-tight ● Why? ● Examples: feathers, hair, scales

Respiration & Circulation ● Respiration (breathing): ● Aquatic = gills ● Terrestrial = lungs ● Circulation: ● Closed circulation with multi-chambered heart ● Separates oxygen and deoxygenated blood ● Improves efficiency

Digestion & Excretion ● Digestion: ● Occurs in the gut (mouth → anus) ● Excretion: ● Kidneys: filters wastes from the blood while regulates water levels in the body

Nervous System ● Highly organized brains ● Each part has its own function

Fertilization & Development Section 32.3

Fertilization ● Definition: the union of the female and male reproductive gametes ● Results in a single diploid cell named the zygote I’m in!

Fertilization Steps: 1. Sperm’s membrane fuses with egg’s membrane 2. Electrical charge occurs to block entry of other sperm into egg 3. Sperm nucleus merges with egg nucleus forming zygote 4. DNA replication begins & cell division occurs V IDEO

Cleavage ● Definition: division of the zygote immediately following fertilization via mitosis ● Organism size does not increase even though number of cells does

V IDEO

Tissue Development ● Cleavage results in the formation of a hollow ball of cells called the blastula

Blastula The blastocoel is the center cavity of the blastula with 1 germ layer (blastoderm)

Tissue Development ● The blastula invaginates ● folds inward at one point ● Called Gastrulation ● The opening is called the blastopore ● The center is the primitive gut ● Archenteron blastopore Archenteron

Embryonic Development V IDEO

Tissues

Tissue Development: ● Germ layers: tissues found in the embryos of all animals except sponges ● Typically three layers in depth ● All body features arise from one of these layers ● Body cavities: fluid-filled space that forms between the digestive tract & outer wall of body during development ● Aids in movement of animal ● Reservoir for transport of materials

Germ Layers ● Form tissues, organs, & systems ● NOT present in sponges ● Ectoderm (outer) – forms skin, nerves, sense organs ● Endoderm (inner) – forms liver and lungs ● Mesoderm (middle) – forms muscles & other systems Animation

Body Cavities

Coelom = Body Cavity ● Internal body cavity fully lined with mesoderm ● Body organs suspended in this cavity

Types of body cavities: 1. Acoelomates: no body cavity ● solid bodies filled with cells ● sponges, cnidarians, & flatworms 2.Pseudocoelomates: “false body cavity” ● have a functional body cavity NOT fully lined with mesoderm ● Rotifer, roundworms 3.Coelomates: true coelom ● Mollusks, annelids, arthropods, chordates

Acoelomate ● no body cavity ● solid bodies filled with cells ● sponges, cnidarians, & flatworms

Pseudocoelomate ● “false body cavity” ● have a functional body cavity NOT fully lined with mesoderm ● Rotifer, roundworms

Coelmate: ● true coelom ● Mollusks, annelids, arthropods, chordates