Biology - Mr. Willets
Animal Kingdom -Part One
The Animal Kingdom contains over 1 million species of organisms. It is difficult to describe animals in a way that includes all these variations so we will stick to the basics.
All animals are multicellular with specialized tissues. Their cells are eukaryotic without cell walls. Animals are heterotrophic and feed mostly by ingestion (they bring food into the body to be digested). Animal embryos go through the basic stages of development including the blastula. About 95% of animals are invertebrates - animals without backbones.
SYMMETRY -Because animals must find their food, movement is often (but not always) a critical trait. The ability of an animal to move is related to the animal's basic shape. The general shape of an organism is called its symmetry.
A) asymmetry- no regular shape. Many sponges are like this. Sponges do not move.
B) radial symmetry - animal has a top and a bottom but no front or rear. A drinking glass is like this.
Radial symmetry is found in many animals that live their lives attached to something. This is called being sessile. It is also a common symmetry found in planktonic (floating) animals.
C) bilateral symmetry- the animal has a front (anterior) and a rear (posterior). It has a top (dorsal) and a bottom (ventral). It has a left and right side.(For some reason, no biologist came up with fancy words for left and right) You are a bilateral animal. Think of yourself on hands and knees. Your head is anterior. Your boom-boom is posterior. Your back is dorsal and your chest/stomach is ventral.
Since bilateral symmetry is associated with moving, these animals usually have sense organs and a brain located at the anterior end. This evolutionary development is called cephalization.
BODY PLANS - Animal bodies have certain features that are common to most animals with some variations.
A) Gut- a space inside the body where food is digested
1) incomplete gut- only one opening into the gut. Food enters and wastes leave through the mouth.
2) gastrovascular cavity- GVC- an incomplete gut that not only digests food but also helps circulate it to body cells (gastro = stomach / vascular = circulation)
3) complete gut- the gut has two openings: a mouth where food enters and an anus where wastes leave.
B) Body cavity- fluid filled space where internal organs are located
1) acoelomate - an animal with no body cavity.
2) pseudocoelomate - in this type of animal, the internal organs are not attached to the outer body wall (this cavity is called a pseudocoelomic cavity- you will see this in lab)
3) coelomate - these animals have their internal organs attached to the outer body wall.(this cavity is called a coelomic cavity - you will see this in lab)
RESPIRATION-oxygen can diffuse into an animal and carbon dioxide can diffuse out only through a moist thin layer of cells. This is called the exchange of gases.
1) diffusion through outer layer of cells- Must be kept moist. Difficult (not impossible) on land. This also means the outer layer must be thin and therefore not offer much protection.
2) gills- these have lots of surface area for diffusion. They are located near the outside of body. These work in water where drying out is not a problem.
3) internal air sacs- lungs. Being inside the body, these are easier to keep moist on land. Lungs do require that air be pumped in and out.
CIRCULATION - moving food, oxygen, wastes et al. around the body.
1) simple diffusion- materials move from cell to cell. This works only in very simple animals.
2) Fluid in the body cavity-not very efficient but can move some materials around.
3) blood- specialized fluid- requires a pump and blood vessels
a) open circulation-blood flows out of the vessels into large areas. Slow and inefficient. Used mostly by some slow or non-moving animals.
b) closed circulation-blood stays in vessels- more efficient. Used by faster moving animals.
Biology- Mr. Willets
Animal Kingdom-1 Questions
1) The general shape of an organism is called its _________________________
2) What type of symmetry do you have? _________________________
3) An animal with radial symmetry often lives its life either _______________ to something or by _____________________ in the water. What word describes the first situation? _________________
What word describes the second? ________________________
4) Sharks have a _________________ fin sticking up out of the water. Since you know this name, it is easier to remember that _______________ means the top of the animal.
5) Which part of you is dorsal? ______________________ This is the top of your body when you are in what position? ________________________________
6) The front of an organism is called the ____________________ ("ante" means front or before)
The rear of an organism is called its ____________________ ("post" means after or behind)
7) What is usually located at the anterior or head end of an animal? _____________________________
This is called ____________________________ ("cephal" means head)
8) Food is digested in a space called the ______________ If this has only one opening, it is called an _________________________________ If it has two openings, it is called a __________________
___________. What are the two openings? ______________ and _________________
9) GVC stands for ______________________________________ This is a gut that also helps to _______________________ the digested food. What part of the name tells you about this second function? _________________________
10) Acoelomates have no ____________________________. Coelomates have a body cavity where the __________________________ are attached to the ___________________________.
In _____________________________________, these are not attached.
11) What gas must be brought into animals? ______________________ What gas must leave?_____________________ This is called respiration or the __________________ of ________________
12) The exchange of gases must take place through a layer of cells that is __________________.
13) Using the skin for respiration is tough on land because it must be kept ______________ It also has to be ____________ and therefore cannot _______________ the animal very well.
14) A specialized structure for respiration that many aquatic animals have is the _______________. These have a lot of ____________________ area. These are located near the _______________ of the body. These work only in _____________ where _____________________ is not a problem.
15) Advanced land animals use _______________ to get oxygen. These are located _______________ the body where they can stay moist.
16) The best method for moving materials around the body uses ______________. Basic diffusion works only in very __________________ animals.
17) If the blood stays in the blood vessels, it is called __________ circulation. This is found in most ____________ moving animals. If the blood leaves the vessels for a time while it circulates, it is called ______________ circulation and is used by animals that are slow or some that don't ___________ at all.