Introduction to Animals (26-1)

What is an animal? Animals belong to the Kingdom Animalia and are: Multicellular Eukaryotic Heterotrophs Cells have no cell wall Invertebrates- no backbone: sea star, worm, jellyfish Vertebrates- backbone: fish, amphibian, reptile, bird, mammal Animals contain tissues- groups of cells that function together. There are these types of tissues in animals: Epithelial Muscular Connective Nervous

What do animals need to do to survive? Carry out the following functions: Feeding Respiration Circulation Excretion Response Movement Reproduction Most of these functions involve feedback inhibition- the product or result of the process stops or limits the process. Example: A stimulus- body heat makes a response- sweating. When body temperature returns to normal, the sweating stops.

Feeding Most animals need to ingest their food. herbivores – eat plants carnivores – eat other animals omnivores – eat plants and animals detrivores – eat decaying materal filter feeders – strain tiny organisms from water symbiosis– lives within another organism Respiration All animals take in oxygen and release carbon dioxide. diffusion- respire through thin-walled bodies complex systems and organs to exchange gases- lungs, gills, etc.

Circulation All animals need a way to transport oxygen, nutrients, and waste throughout their bodies. simple diffusion- thin layers of cells, smaller animals circulatory systems- larger animals Excretion Animals must have a way to rid their bodies of ammonia- a waste with lots of nitrogen that if it builds up it is poisonous to animals. excretory system- converts ammonia to a less toxic product and then removes it from body. Example- kidneys simple systems- cells that get rid of water

Response Animals use nerve cells to respond to events in their environments. Arrangement of nerve cells is drastically different from animal to animal. Nervous System- cells arranged together in more complex animals to respond to sound, light, and other stimuli. Nerve Cells- process information to determine response Movement Muscles working together with skeleton create movement in animals. Motile- highly developed muscular/skeletal systems that enable animals to move from place to place. Sessile- stay attached to single spot.

Reproduction Animals need to reproduce to increase their species over time. Sexual-making haploid gametes to increase genetic diversity in populations and allow evolution. Asexual- many invertebrates use asexual reproduction to increase numbers rapidly without genetic variation. Review: List the seven things animals need to survive. (F, R, C, E, R, M, R)

Trends in Animal Evolution Complex animals tend to have high levels of cell specialization and internal body organization bilateral symmetry a head with sense organs a body cavity Cell Specialization The more complex an animal is, the more specialized its cells need to be to carry out functions. Example- amoeba (single cell organism) can use simple diffusion for many life functions. However a large mammal has many cells that are specialized in structure and function to perform their jobs.

Each layer gives rise to the systems (specialized cells) the body. Early Development As a cell becomes two cells, then divides to eventually become a blastula, the layers that develop next indicate the body complexity in each species of animal. Each layer gives rise to the systems (specialized cells) the body. Zygote 2 Cell Stage 16 Cell Stage Blastula Blastopore- central tube of development

A blastula can develop into: Protostome- an animal whose mouth is formed through the blastopore OR 2) Deuterostome- an animal whose anus is formed through the blastopore Echinoderms (starfish) and All Vertebrates are deuterostomes- suggests a closer evolutionary relationship

During early development, the cells of most animal embryos differentiate into three layers called germ layers: Layer Description Develop Into: Endoderm Inner most germ layer Linings of digestive tract and respiratory system Mesoderm Middle germ layer Muscles, circulatory system, reproductive system, excretory system Ectoderm Outer most germ layer Sense organs, nerves, outer layer of skin

Body Symmetry Except for sponges, all animals demonstrate some kind of symmetry. Radial Symmetry- suggests lower complexity, simpler organism. Example: sea anemone

Bilateral Symmetry- suggests higher complexity in organisms. Directional Terminology: Anterior- front end Posterior- back end Dorsal- upper side Ventral- lower side *Bilateral Symmetry usually indicates segmentation as well- with each segment specialized in function.

Cephalization Animals with bilateral symmetry usually exhibit cephalization- the concentration of sense organs in the front end of the body (brain in a head). Animals with cephalization respond to the environment more quickly and in more complex ways. Usually move with their anterior end forward. Body Cavity Formation Most animals have a body cavity- a fluid-filled space that lies between the digestive tract and body wall. A body cavity is important because it provides space and protection for organs. Body cavities also allow for specialized regions to develop.

Comparing INvertebrates Chapter 29

29-1 Invertebrate Evolution What are invertebrates? Invertebrates make up 95% of the animal kingdom. Invertebrates are any animal without a backbone What are the main classifications of invertebrates? Sponges Cnidarians- jellyfish, sea anemones Worms- round worms, flat worms, annelids Mollusks- clams, snails, octopus Arthropods- insects, crabs, spiders Echinoderms- sea stars, sea cucumbers

The First Multicellular Animals Were probably simple and had little internal specialization. Then in the Cambrian Period many more diverse invertebrates were on earth. They had evolved shells, skeletons, and other hard body parts, specialized cells, tissues, and organs. This is referred to as the “Cambrian Explosion.” These new invertebrates are the most similar to modern invertebrates of today and may be ancestors of invertebrates of today. What features made the Cambrian Explosion animals so successful? Body symmetry, segmentation, skeleton, front and back end, adapted appendages.

Invertebrate Phylogeny Look at Figure 29-4 on page 747 1) What does this diagram demonstrate? Evolution of major features in invertebrates 2) What derived character is unique to echinoderms and chordates only? deuterostome development 3) What does this say about the relationship between echinoderms and chordates? they are most closely related to each other 4) What derived character separates sponges from cnidarians? tissues 5) What derived characters do all animals have in common? Multicellular

Evolutionary Trends Specialized Cells, Tissues, and Organs As more sophisticated invertebrates evolved, internal specialization evolved from: cells---tissues----organs----organ systems Examples: Sponges Flatworms Mollusks Cnidarians Arthropods Body Symmetry All invertebrates except sponges exhibit some sort of body symmetry: 1) Radial Symmetry- Cnidarians, Echinoderms 2) Bilateral Symmetry- Worms, Mollusks, Arthropods

Cephalization The evolution of bilateral symmetry and the lifestyle of relying on movement for feeding, defense, and other important functions was accompanied by the trend of: cephalization- the concentration of sense organs and nerve cells in the front of the body. examples: collection of nerve cells called ganglia, or a brain. Segmentation Most invertebrates with bilateral symmetry have segmented bodies. Different segments have evolved to perform specialized functions. Example: thorax of Insect with wings

Coelom Formation coelom- body cavity that forms between germ layers- offers protection for organs and organ systems. Invertebrates differ in the arrangement of germ layers: Acoelomate Pseudocoelomate Coelomate Ex: Flatworms Ex: Roundworms Ex: Annelids Embryological Development All Invertebrates except Echinoderms: Protostome Echinoderms: Deuterostome

29-2 Form and Function in Invertebrates Biologists learn a great deal about the nature of life by comparing the body systems that deal with: Feeding and Digestion Respiration Circulation Excretion Response Movement and Support Reproduction Simple Animals use: Intracellular Digestion Complex Animals: Extracellular Digestion Extracellular Digestion can be: A single opening – mouth = anus (two-way) Two openings - mouth and anus separate (one-way) A system of organs that work in a specific order

Respiration All Respiratory organs have a large surface area that are in contact with air or water. They also must be moist for diffusion to occur. Aquatic Invertebrates: - Some respire through moist skin - Some use gills Terrestrial Invertebrates: - Mantle cavity example- Mollusks - Book Lungs example- Spider - Spiracles example- Insects Circulation Most complex animals move blood through their bodies using one or more hearts and either an open or closed circulatory system.

Open Circulatory System Blood is only partially contained in blood vessels. One or more hearts pump blood through blood vessels into a series of sinuses or spongy cavities. The blood comes into direct contact with the tissues and eventually makes its way back to the heart. Examples that OCS: arthropods and mollusks Closed Circulatory System A heart forces blood through vessels throughout the body. The blood stays within the vessels. Materials reach the body by diffusing through the vessels. More active animals need this high pressure system for efficient delivery of blood to the body Examples of CCS: Annelids and some Mollusks

Open Circulatory vs. Closed Circulatory Sinuses and Organs

Excretion Most animals have a excretory system that rids the body of metabolic wastes while controlling the amount of water in the tissues. There are a variety of ways invertebrates can do this, mainly depending on if they are Aquatic or Terrestrial. Aquatic Excretion – Mostly excrete ammonia using diffusion into the surrounding water. - It is very important that freshwater inverts rid themselves of excess water. Terrestrial Excretion – Most need to conserve water, and rid themselves of waste. - This is done using organs and organ systems designed to make urine.

Response Invertebrates show three trends in the evolution of the nervous system in varying degrees of: 1) Centralization 2) Cephalization 3) Specialization Simple ------------- Nerve net that encompasses most of the body Centralization of clumps of nerve cells called ganglia. Complex ----------- Cephalization (brain) Specialization- The more complex the nervous system the more developed sense organs are.

Exoskeleton- Hard outer covering made of chitin. Movement and Support Invertebrate have one of three kinds of skeletal systems: Hydrostatic Exoskeletons Endoskeletons Hydrostatic- Animals have muscles that surround a fluid filled body cavity that supports the muscles. Muscles contract- push the fluid in the cavity- body changes shape Exoskeleton- Hard outer covering made of chitin. Movement occurs when muscles that are attached to the inside of the exoskeleton contract. Endoskeleton- Structural support that is inside the body. Movement occurs when muscles attached to the internal skeleton contract.

Reproduction Invertebrates use a combination of sexual and asexual reproduction. Asexual is fast and takes advantage of favorable conditions. Sexual ensures genetic diversity. Most animals are either male or female, but some are hermaphrodites (like earthworms) External Fertilization- Eggs are fertilized outside of the female’s body. Internal Fertilization- Eggs are fertilized inside of the female’s body.