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By the end of this section, you will be able to:
  • Describe the various types of body plans that occur in animals
  • Describe limits on animal size and shape
  • Relate bioenergetics to body size, levels of activity, and the environment

Animals vary in form and function. From a sponge to a worm to a goat, an organism has a distinct body plan that limits its size and shape. Animals’ bodies are also designed to interact with their environments, whether in the deep sea, a rainforest canopy, or the desert. Therefore, a large amount of information about the structure of an organism's body (anatomy) and the function of its cells, tissues and organs (physiology) can be learned by studying that organism's environment.

Body plans

Illustration A shows an asymmetrical sponge with a tube-like body and a growth off to one side. Illustration B shows a sea anemone with a tube-like, radial symmetrical body. Tentacles grow from the top of the tube. Three vertical planes arranged 120 degrees apart dissect the body. The half of the body on one side of each plane is a mirror image of the body on the other side. Illustration C shows a goat with a bilaterally symmetrical body. A plane runs from front to back through the middle of the goat, dissecting the body into left and right halves, which are mirror images of each other. The top part of the goat is defined as dorsal, and the bottom part is defined as ventral. The front of the goat is defined as anterior, and the back is defined as posterior.
Animals exhibit different types of body symmetry. The sponge is asymmetrical, the sea anemone has radial symmetry, and the goat has bilateral symmetry.

Animal body plans follow set patterns related to symmetry. They are asymmetrical, radial, or bilateral in form as illustrated in [link] . Asymmetrical animals are animals with no pattern or symmetry; an example of an asymmetrical animal is a sponge. Radial symmetry, as illustrated in [link] , describes when an animal has an up-and-down orientation: any plane cut along its longitudinal axis through the organism produces equal halves, but not a definite right or left side. This plan is found mostly in aquatic animals, especially organisms that attach themselves to a base, like a rock or a boat, and extract their food from the surrounding water as it flows around the organism. Bilateral symmetry is illustrated in the same figure by a goat. The goat also has an upper and lower component to it, but a plane cut from front to back separates the animal into definite right and left sides. Additional terms used when describing positions in the body are anterior (front), posterior (rear), dorsal (toward the back), and ventral (toward the stomach). Bilateral symmetry is found in both land-based and aquatic animals; it enables a high level of mobility.

Limits on animal size and shape

Animals with bilateral symmetry that live in water tend to have a fusiform    shape: this is a tubular shaped body that is tapered at both ends. This shape decreases the drag on the body as it moves through water and allows the animal to swim at high speeds. [link] lists the maximum speed of various animals. Certain types of sharks can swim at fifty kilometers an hour and some dolphins at 32 to 40 kilometers per hour. Land animals frequently travel faster, although the tortoise and snail are significantly slower than cheetahs. Another difference in the adaptations of aquatic and land-dwelling organisms is that aquatic organisms are constrained in shape by the forces of drag in the water since water has higher viscosity than air. On the other hand, land-dwelling organisms are constrained mainly by gravity, and drag is relatively unimportant. For example, most adaptations in birds are for gravity not for drag.

Maximum Speed of Assorted Land Marine Animals
Animal Speed (kmh) Speed (mph)
Cheetah 113 70
Quarter horse 77 48
Fox 68 42
Shortfin mako shark 50 31
Domestic house cat 48 30
Human 45 28
Dolphin 32–40 20–25
Mouse 13 8
Snail 0.05 0.03

Questions & Answers

what difference between animal cell and plant cell
Lazarus Reply
what is animal call
what is fertilization?
Muhamed Reply
What kind of nutrients is composed of plants
Annie Reply
what is hormones
Igwe Reply
hormon is the chemical messanger
Genes can make someone dull?
21ecological instrument and their diagrams
Ayomide Reply
cell biology
I am sorry
for wat
no reason
nothing but speculate
what are the kidney disease
Immaculate Reply
kidney stones
it is a disease that affects the kidney
what are some lung diseases
what is micro-organism
Jackson Reply
what is the hypothesis
hypothesis is a proposed explanation for a phenomenon
hypothesis is raw materials
what is biology
biology is the study of living things and their interaction with their environment
what is zyogot?
what is fertilization?
zygote is an unfertilized eggs
fertilization refers to the fusion of a sperm and ovum
what does mean stigma
Amira Reply
what is the full of the MOST dangerous disease in the world where one stops sleeping and just dies :Hint ; FFI
God Reply
fatal familial insomnia which affects the thalamus
there are other dangerous diseases like CAD i.e coronary artery disease
what is matter
Thomas Reply
it is any thing that has weight and occupies space
matter is any substances that occupies spaces and has mass
describe photosynthesis
Mavis Reply
What is equilibrium
What is equilibrium
like corporal intern balance right?
on my own understanding is just a balanced state
photosynthesis is the process by which plants and other organisms convert light energy to chemical energy
what is a chromosome?
Wise Reply
Are thread-like structures located inside the nucleus of animal and plant cells.
what are the difference between Biotic community and Ecological nitche.
Ganiyat Reply
what is the celll
A cell is the simplest bit of living matter that exist independently
cell is the basic unit of life
what is ecdysis
what is genetics
Sebastian Reply
The cell is the simplest bit of living matter that can exist independently.

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Source:  OpenStax, Biology. OpenStax CNX. Feb 29, 2016 Download for free at http://cnx.org/content/col11448/1.10
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