Chapter 26-1 Introduction to the Animal Kingdom What is an animal?

Members of the Kingdom Animalia Multicellular Eukaryotic cells whose cells lack a cell wall Heterotrophs

Animals have: i. Epithelial tissue - covers the body surfaces, lines the inside of tubes found in the body and form the glands of an animal. -cells tend to be thin, flat structures through which gases and nutrients can move through. ii. Muscle tissue

iii. Connective tissue iv. Nervous tissue

95% of animals are categorized as invertebrates. -range in size from microscopic dust mites to the giant squid which is more than 20 meters long. -include sea stars, sponges, jelly fish, worms, insect, clams. -5% of animals are categorized as vertebrates - includes fishes, amphibians, reptiles, birds and mammals.

What do animals do to survive? Essential functions include: Feeding. Respiration Circulation Excretion Response Movement Reproduction.

Homeostasis is often maintained by internal feedback mechanisms called feedback loops. Feedback loops involve feedback inhibition in which the product or result of a process stops or limits the process. Ex. When a dog becomes to hot it pants – panting releases heat – body temperature of the dog cools – dog stops panting.

Feeding -Absorb food, ingest food? -Herbivore, carnivore, amnivore, detrivore? -Filter feeder? -Symbiotic relationship/ parasisitic?

Respiration Transport of Oxygen and Carbon dioxide. Aquatic or Terrestrial? Simple system of diffusion or a Complex system involve different organs?

Circulation Transport of gases, nutrients and waste products. Aquatic vs Terrestial animals? Simple diffusion vs circulatory system?

Excretion Elimination of waste products -Ammonia, urea, uric acid – elimination of excess nitrogen. -elimination of excess salts, water

Response -responding to external environment Specialized nerve cells? Nervous System -responding to internal environment Hormones?

Movement Sessile? Motile? Cilia? Flagella? Muscle cells? Muscle System? Skeleton?

Reproduction Asexually? Sexually?

Trends in Animal Evolution Complex animals tend to have high levels of cell specialization and internal body organization, bilateral symmetry, a front end or head with sense organs and a body cavity.

Early Development Animals that reproduce sexually begin life as a Zygote ( 2n) or fertilized egg (2n). Embryology is the study of embryo development

Draw out diagram from text p 661 Blastula – hollow ball of cells which develops into either a protostome or deuterostome Blastula – formation of a blastopore – inward indentation of the blastula in the centre of the blastula – this tube becomes the digestive tract and is formed in one of two ways:

1. Protosome -mouth is formed from the blastospore – incl most invertebrates. Deutrosome -an animal whose anus is formed through the blastospore – the mouth is formed 2nd after the anus. -includes echinoderms and all vertebrates

During early development, the cells of the embryo develop (differentiate) into three layers called germ layers. Endoderm – inner most germ layer – develop into the linings of the digestive and much of the respiratory organ systems. Mesoderm - middle layer – differentiates into muscles and much of the circulatory, reproductive and excretory organ systems Ectoderm - outermost layer – gives rise to sense organs, nerves and the outer layer of skin.

Body Symmetry -except sponges Radial Symmetry -body parts that repeat the centre of the body – sea anemone, sea stars, etc. Bilateral Symmetry -can divide the body into two equal halves- left and right sides – usu have a front (anterior) and back (posterior) ends and upper (dorsal) and lower (ventral) sides.

An anatomy with bilateral symmetry allows for segmentation in which the is constructed of many repeated and similar parts or segments. Also animals with b.l. symmetry have external body parts that repeat on either side of the body – arms, legs, etc.

Cephalization Is the concentration of sense organs and nerve cells at the front end of the body. Increased cephalization – animals can respond to their environment quickly. Move with anterior end forward, so this end comes into contact with new parts of the environment first.

Body Cavity Formation Fluid filled space that lies between the digestive tract and the body wall. Provides a space in which internal organs can be suspended so that they are not pressed on by muscles or twisted out of shape by body movements. Also allow for specialized regions to develop