Biology 11: Overview of Animals

Overview of Animals (p 730…)

•less than 5% of animal phyla have backbones- called __ vertebrates eg.__ fish, amphibians, reptiles etc •more than 95% do not-called_invertebrates eg. earthworms, insects, snails, etc.•more than one million

animal species identified - probably millions more not identified

A. Characteristics of AnimalsAll Animals...

1. eukaryotic cells 2. multicellular (specializedcells) 3. cells do not have cell walls (therefore felxible) 4. heterotrophic 5. motile (or at least a motile stage in life cycle)

As well, MOST animals... •have specialized tissues and organs

•are heterotrophic by ingestion•have two unique types of tissues responsible for impulse conduction & movement:nervous tissue & muscle tissue

•similar early embryonic development How have various animals adapted to a motile lifestyle?legs, flippers, wings, tails, tentacles=appendagesWhat characeristics do animals share with other organisms?eukaryotic cells, heterotrophci, multicellular, motility, sex.repr. spec. tissues and organsWhat characteristic(s) distinguishes animals from other organisms?asexual repro not common,all motile/motile stage, nerve and muscle tissue, unique embryonicdevelopmentWhy would body cells with rigid cell walls be a disadvantage to animals?interfere with movement (not flexible)

B. Essential Functions of Animals (ch 27 and 28) 1. Support and movement (p814-817) (firm enough to

support;flexible enough to move)

Biology 11: Overview of Animals

Some animals are sessile which means they live their entire adult lives attached to one spot, but many animals are motile, which means that they move around.•To move, most animals use tissues called musclesthat generate force by contraction.•In the most successful groups of animals, muscles work together

with a skeleton, or the system of solid support in the body. There are 3 types of skeletal systems:

a) exoskeleton - hard encasement on surface of animal, eg. insects, crabs, snails, clams, etc. ---> limits growth & flexibility

b) endoskeleton - rigid framework inside animal ---> doesn’t protect as well as an exoskeleton, but

allows for freer movement, eg. birds, reptiles, mammals, etc.

c) hydrostatic - some animals do not have a system of solid support, but instead muscles surround and are supported by a water-filled cavity, eg. earthworm

2. Feeding and Digestion (p. 782-785)•to supply energy (for movement, etc.) & nutrients for growth, repair, etc., animals must find, break down & absorb food to do this•animals have different modes of feeding (ways of obtaining food)

Biology 11: Overview of Animals

Complete the following chart, which Mode of Feeding Description Examples

Filter Feeder Strain food (algae and small animals from H2O…use modified gills or other structures)

Sessile worms, sponges, barnacles, some sharks and whales

Detritus Feeder Feed on tiny bits of decaying plants and animals, bacteria, algae, etc.

Earthworms, marine worms, crustaceans, (carbs and lobsters etc.)

Herbivores Feed on plants, plant parts eg. Roots, stems, flowers, fruit, leaves, sap

Some birds, and mammals, insects

Carnivores Eat animals, parts of animals

Mammals, wolves etc. spiders, cnidarians, hydra, insects,etc.

Omnivores Eat both plants and animals

Humans, bears

Parasitic Symbionts Live on or in another, feed on tissue/blood/other fluids

Parasitic roundworms & flatworms (tapeworms) fleas, lice

Mutualistic Symbionts Both organisms benefit Corals and algae in their tissues, termites and gut protists

Biology 11: Overview of Animals

compares different modes of feeding.

•digestion can be intracellular (in simple animals) or extracellular (in digestive tract) Intracellular digestion: digest food inside

specialized cells by diffusion (sponges)

Biology 11: Overview of Animals

Extracellular digestion: food is broken down outside cells in a

digestive system and then asorbed

•digestive cavity can be one-way or two-way

3. Gas

Exchange (Respiration) (p. 787)•Living cells consume oxygen & give off carbon dioxide in the process of aerobic cellular respiration•Entire animals must respire, or breathe, in order to take in & give off these gases•Diffusion of gases between the environment & animals requires a thin moist membrane•Small animals that live in wtaer or in moist soil may respire through their skin•Large animals - respiration through skin not efficient enough - respiratory systems have taken many different forms in adapting to different habitats

4. Sensing the Environment (Nervous System) (p. 808)•Animals must keep watch on their surroundings to find food, spot predators, & identify others of their own kind (for mating, etc.).•To do this, they use nerve cells, which hook up together to form a nervous system•the simplest nervous systems are called nerve nets•Sense organs, such as eyes & ears, gather information from the environment by responding to light, sound, temperature & other stimuli

Biology 11: Overview of Animals

•Brain - nervous system’s control centre - processes information & regulates

how the animal responds•complexity of nervous system varies greatly in animals

5. Internal Transport (Circulatory System)(p. 791-792)•Some aquatic animals, such as small worms, can function without an internal transport system •in small animals, simple diffusion between their body & the environment is sufficient

•Larger animals must carry oxygen, nutrients & waste products to & from cells deep within its body

•Many have evolved circulatory systems in which a pumping organ called a heart forces a fluid called blood through a series of blood vessels•circulatory systems can be open or closed:

open circulatory system: blood is NOT always confined to blood vessels (there are blood cavities/sinuses)

closed circulatory system: blood is always confined to blood vessels

6. Excretion (p. 794)•Cellular metabolism produces chemical wastes such as ammoniathat are harmful & must be eliminated•ammonia (NH3) is produced by the breakdown of amino acids in proteins•toxic nitrogen-containing compounds are called nitrogenous wastes•Small aquatic animals depend on diffusion to carry wastes from their tissues into the surrounding water, which then carries wastes away•Larger animals (in water & on land) must work to remove poisonous metabolic wastes

NOTE: EXCRETION IS NOT THE SAME AS ELIMINATION OF UNDIGESTED WASTE (FECES)

Biology 11: Overview of Animals

7. Reproduction (p. 819)

•Animals must reproduce or their species will not survive.

•Some (like jellyfish) switch back & forth between sexual and asexual reproduction•All animals reproduce sexually(some asexually also)•Sexual reproduction - can bear live young or lay eggs•Direct development: eggs of some species hatch into baby animals that look like miniature adults ---> babies

increase in size, don’t change in overall form•Indirect development: eggs hatch into immature stages that look & act nothing like the parents (called larvae) ---> larvae undergo process called metamorphosis in which they change shape

dramatically as they grow

C. Characteristics Important in Classifying Animals (p 737…) 1. Symmetry

•refers to the way the animal’s organs & other structures are arranged•must make animal an efficient organism that can compete in its environmenta) asymmetric (no symmetry)b) radial symmetry - has ventral &dorsal surfaces (does not have front, back, right or left side)

•tend to be slow moving or sessile•sense organs located in radial pattern around body

(Why is such an arrangement of sense organs an advantage to slow-moving or sessile organisms?

Biology 11: Overview of Animals

c) bilateral symmetry -

parts arranged in pairson either side of a central axis

•generally more complex organs (concentrated at head end -enables efficient movement (Why?)

•several terms are used to describe the body of an organism that has bilateral symmetry

•anterior: head end•posterior: tail end

•ventral: belly or underside•dorsal: back or upperside

•medial: middle•lateral: to the side

2. Segmentation (p 739)•some or all of body divided into repeating units or segments•may be obvious from outside or not (eg. vertebrae - each one represents a segment)•segments may be fused together into larger functional units (eg. chest or abdomen)•segmentation enables specialization of body parts & more complex bodies over all

Biology 11: Overview of Animals

3. Level of Organization•cellular: cells not organized into tissues (but cells are specialized

tissues: cells organized into tissues eg. Epithelial, nervous, muscle, connective

•organs: tissues organized into organs(eg.heart, kidney, stomach•organ systems: organs organized into systems(egreproductive, nervous, circulatory•level of organization dependent upon number of germ cell layers

•patterns of tissue development in embryos very similar to blastula stage (blastula - hollow ball; gastrula - 2-layered cup-shaped embryo)

•during formation of gastrula, cell layers develop that will give rise to different tissues & organs•the number of cell layers & the way the embryo develops from gastrula stage varies with the kind of animal•most animals have 3 layers:

•ectoderm---> skin, nerves & sense organs

•mesoderm ---> circulatory system, muscles, reproductive & excretory system

•_endoderm ---> digestive tract & respiratory system

Biology 11: Overview of Animals

4. Body Plan(see “type of digestive tract”)•sac plan: mouthused for taking in food, getting rid of wastes•tube-within-tube: mouth takes in food, anus gets rid of wastes

•some animals have NO body plan 5. Coelom (Body cavity between digestive tract & body

wall)a) Coelomates: have true coelom (a fluid-filled body cavitycompletely lined with mesoderm that contains internal organs)

b) Pseudocoelomates: have false coelom - coelom only partially lined with mesoderm

c) Acoelomates: have no coelom (only fluid-filled extracellular spaces)

D. Questions 1. a. Explain “cephalization. (p740

b. what types of animals have pronounced cephalization?

c. Why do animals with heads usually move in a “head-first” direction?

2. Study the chart on p 741, which illustrates several important evolutionary trends. As animals become more complex, state the evolutionary trend with respect to:

a. Level of organisation

Biology 11: Overview of Animals

b. body symmetry

c. Germ layers

Biology 11: Overview of Animals