Biol 11 Lesson 1 Feb 1 - Ch 26 Introduction to the Animal Kingdom

Warm-up activity!

What do the following images have in

common?

What do we have in

common?

That’s right—we’re all animals!

Good job!

Which of us are

invertebrates?

What is an invertebrate?

invertebrate – animal that does not have a backbone

vertebrate – animal that has a backbone

Note:Terms in green are definitions

– these are key terms to know

Terms in blue are important words or concepts

- please make note

Biology fun fact of the day:

Over 97% of all animal species are invertebrates!!!

Invertebrates are by far the larger group.

• Invertebrates make up 9 different phyla!• Vertebrates all belong to 1 phylum (Phylum Chordata)

Introduction to the Animal Kingdom: Invertebrates

Chapter 26: Sponges, Cnidarians, and Unsegmented Wormspp. 554-560

What is an animal?General characteristics:

•A heterotroph - an organism that cannot produce its own food▫ Obtains nutrients and energy needed by feeding on organic

compounds made by other organisms

•Multicellular – composed of more than one cell

•Eukaryotic – cells contain a nucleus and membrane-enclosed organelles▫ Unlike plant cells or fungus cells, animal cells do not have

cell walls

• Internal digestion

•Generally move at some point in their life

•Animal - A multicellular eukaryotic heterotroph whose cells lack cell walls.

Multicellularity

Why did multicellular organisms evolve from unicellular ones in the first place?

Reason 1: Because bigger is better! ▫Avoid being eaten▫Have greater choice of organisms to eat

•Single-celled organisms kept increasing in size (strong selection pressure to be large) until the upper size limit for single cells was reached.

Volume = (L X W X H)

Surface area = (L x H)

S.A./vol. ratio

Cell 11 cm x 1 cm x 1 cm = 1 cm3

(1 x 1) x 6 = 6 cm2

6:1

Cell 22 cm x 2 cm x 2 cm = 8 cm3

(2 x 2) x 6 = 24 cm2

24:8 or 3:1

Cell 33 cm x 3 cm x 3 cm = 27 cm3

(3 x 3) x 6 = 54 cm2

54:27 or 2:1

O2, CO2, nutrients and wastes must diffuse through the cell’s surface. Cell 1 has a high S.A./vol. ratio lots of surface area for diffusion. Cell 1 is efficient!Cell 3 has the lowest S.A./vol. ratio; it is much less efficient than Cell 1. Cell 3 has a harder time carrying out everyday metabolic processes because it takes much longer for particles to diffuse to the cell’s centre.

6 sides on a cube

• In short: A high surface area to volume ratio (S.A./vol. ratio) is beneficial to a cell. It is easier to be efficient if you’re small.

• It is easier to carry out metabolic processes if you are a small cell, but it is better to be large if you don’t want to be eaten.▫ The evolution of multicellularity solved this dilemma.

Example organisms:

Organism ‘A’ is composed of many small cells; ‘B’ is one single, large cell. Both organisms have about the same volume, but ‘A’ has a lot more S.A. available for diffusion. This gives ‘A’ an advantage over ‘B’.

A B

Multicellularity

*Reason 2: Cells can specialize (division of labour)

(p. 556)▫ If cells can specialize into tissues or organ

systems, the whole organism is more efficient.▫Each specialized cell is uniquely suited to

perform a particular function within a multicellular organism.

•Division of labour – phenomenon in which groups of specialized cells carry out different tasks in an organism

Advantages to Cell Specialization• Large numbers of cells growing together

cannot function the way single cells do (e.g. monerans and protists)

•Cells require a certain amount of surface area to take in food and oxygen and remove wastes▫ Cells that grow together have little, if any, of their surface

exposed to the environment

▫ No efficient systems to carry out essential functions (feeding, respiration, and elimination of wastes) cells starved for food and oxygen and smothered in carbon dioxide and other wastes

• In multicellular organisms, efficient systems require specialization.

specialized cells vs. unspecialized cells

MORE EFFICIENT LESS EFFICIENT

$

Animal Survival• In order to survive, animals must be able to

perform essential functions ▫This is accomplish with their specialized body

systems.

• In the Animal Biology unit, we will examine these body systems and focus on the cells, tissues, organs, and organ systems that perform these functions.

The Invertebrate Phyla1) Sponges2) Cnidarians (e.g. jellyfish)3) Flatworms (e.g. tapeworms)4) Roundworms (e.g. nematodes)5) Mollusks (e.g. clams, snails, octopus)6) Annelids (e.g. earthworms)7) Arthropods (e.g. insects, crustaceans,

spiders)8) Echinoderms (e.g. starfish)9) Invertebrate chordates (small group; the

“link” between vertebrates and invertebrates)* Vertebrates share a phylum with these

(called Subphylum Vertebrata”)

Trends in Animal Evolution

•We will observe a few important evolutionary trends and patterns as we move from one animal phylum to the next.

Trends in Animal Evolution1. The levels of organization become higher

as animals become more complex in form▫ Less complex animals life functions carried out on the

cell or tissue level of organization▫ More complex animals increase in the number of

specialized tissues; these tissues join to form more specialized organs and organ systems

Less complex animals More complex animals CELL OR TISSUE ORGAN OR ORGAN SYSTEM

ORGANIZATION ORGANIZATION

Trends in Animal Evolution2. Some of the simplest animals have radial

symmetry; most complex animals have bilateral symmetry▫ Radial symmetry - body parts repeat around an

imaginary line drawn through the centre of their body Animals with radial symmetry have no true “head” and

most are sessile

Trends in Animal Evolution▫ Bilateral symmetry – body parts repeat on either side of

an imaginary line drawn down the middle of their body (i.e. one side of the body is the mirror image of the other) Animals with bilateral symmetry have specialized front and

back ends as well as upper and lower sides

Trends in Animal Evolution

*See Symmetry handout for more examples.

Trends in Animal Evolution

Anterior - front endPosterior – back endDorsal – upper sideVentral – lower side

Trends in Animal Evolution3. More complex animals tend to have a

concentration of sense organs and nerve cells in their anterior (head) end▫ Animals with bilateral symmetry move with their anterior

end forward encounter new parts of their environment with the anterior end

▫ Therefore, sense organs are concentrated in the anterior end

▫ Cephalization – the gathering of sense organs and nerve cells into the head region; more pronounced in more complex organisms (those with bilateral symmetry)

▫ Ganglia (singular: ganglion) – small clusters of nerve cells; ganglia gather together to form brains in the most complex animals

Finito!

Activity: Concept map

anterior

ganglia

bilateral symmetry

Animals who exhibit this kind of symmetry

show pronounced

…

cephalization

Animals who exhibit this kind of symmetry have a

specialized front end referred to as the …

In this region of the animal,

there is often a concentration

of …

…is the gathering of these clusters of nerves in the head region.

Word bank:bilateral symmetry

gangliacephalization

anterior

Activity: Concept MapDirections: Create a concept map using the terms listed on your handout. Try to make more than 1 or 2 connections between terms. Write a full sentence and draw arrows to connect the terms together.

Homework for next class:• Complete Section Review 26-1 questions 1-5 (p.

560)

• Complete Introduction to the Animal Kingdom: Concept map (if not already finished in class)

• Read over class notes and check out the class blog:http://msoonscience.blogspot.com/

• Return Field Trip form by Feb. 7 – Vancouver Aquarium!

• Bring pencil crayons to class for the upcoming Animal Biology unit - lots of colouring ahead!