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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 is abiotic and biotic factors?
Hira Reply
which of the following shows the correct sequence of the cell cycle
Kameishia Reply
who is name virus
Shivam Reply
centromere consist of
Shivam
meeting point of two chromatids
Cffrrcvccgg
Explain the function of nematocysts in cnidarians?
Israel Reply
The nemotocyst is used by Cnidarians (hydra, jellyfish, sea anemones) to sting their prey and any threatening enemy.
Lee
photosynthesis in plants is an example of what ? (a) excretion (b) irritability (c) nutrition (d) reproduction
Lee Reply
If a Hox 13 gene in a mouse was replaced with a Hox 1 gene, how might this alter animal development?
Israel Reply
Which of the following organisms is most likely to be a diploblast?
Israel
what are reactions of photosynthesis?
Maria Reply
what are the probabilities of blood genotypes for the offspring from a cross between a mother lAlA blood and a father with lBi blood?
dayana Reply
what is matter
Emmanuel Reply
matter is anything that has mass and can occupied space
Alice
weight
Alice
example of matter
Oyekemi
You serves as an example of matter Because matter is anything that has mass and occupy space e.g man and every other things that exist on earth.. So think of every other things around you ...
Biola
and you too
Oyekemi
We generally
Biola
What is ecological management
Oyekemi
how the kidney functions as osmoregulatory organ
Sam Reply
That true
Banda
what is the major connection for sugars in glycolysis?
Ibrahim Reply
Simple term of science
Palesa Reply
what does it mean
gopal
it's means what do u know about biology?
Phathu
what is immunisation
Melysa
the action of making a person immune to infections ,for immunisation
Kalia
what is the biology? what do you know about biology
Phathu Reply
biology is the study of living organisms, divided into many specialized fields that cover their morphology, physiology, anatomy, behavior, origin, and distribution.
Julia
The study of all aspects of life. The study of all living organisms (such as animal cells and plant cells) in greater detail (their structure and how they function). It's a very broad science.
juanita
what is prokaryotic
Bhaskar Reply
what is pathogens
Bhaskar
pathogens are a bacterium, virus, or other microorganism that can cause disease.
Lee
transistion metals....
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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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