Wednesday, November 10, 2010


Body Size and Sexual Dimorphism

Lemurs live in the trees and bushes of Madagascar and the Comores Islands, in which they have a strict diet plan of leaves, fruits, and insects.  Lemurs have reasonably good grip for hanging in trees and rarely come to the ground, except the Ringtail lemur, that actually spends most of its time on the ground.  When lemurs are born, the mother carries her baby in her mouth until they are old enough to hang onto their mother’s fur.  Female lemurs and male lemurs are rather difficult to differentiate from each other.  Lemurs lack sexual dimorphism in size, yet true lemurs show sexual differences in their fur coloration.  Black lemurs have a strikingly obvious difference sexual dimorphism in fur coloration.  The Black lemur got its’ name from the males’ fur coloration, which is black.  However the female Black lemur is brown in color.  Lemurs vary greatly in size and include the smallest primates in the world and the largest ranging in size from the Madame Berthe’s Mouse Lemur (1.1 oz) to the recently extinct Archaeoindris Fontoynonti (440 lb).   Lemurs lack any common characteristics that make them stand out from other primates because they evolved unique combinations of abnormal traits to cope with Madagascar’s harsh climate.

Spider Monkeys
Spider Monkeys, like lemurs, live in trees and rarely come down to the ground.  They reside in the evergreen rainforests and live mostly in the upper canopy.  In order to swing from branch to branch spider monkeys have evolved to possess a third hand!  Their tail is very muscular and actually has a patch of skin with distinct patterns of lines like a fingerprint.  Their tail is able to support their entire weight while their hands forage for food.  The spider monkey is not characterized by a high degree of sexual dimorphism.  However the females play a more active leading role than the males.  When an intruder approaches a Spider Monkeys’ nest, the females will act uncontrollably, displaying wild behaviors and rough barking.

Baboons, like humans, are capable of living in a wide range of habitats.  They are different from lemurs and spider monkeys when it comes to living because they are ground dwelling primates.  Baboons are very clever and like to interact with people.  They are treated as vermin rather than wildlife because they can be agricultural pests with their crafty intelligence.  Baboons have a striking size difference between sexes and coloration.  The males are usually silver/white with a bushy mane around their head and their faces range in color from tan to red.  The females are usually just brown.  Males are drastically bigger than the females in size and are usually very aggressive and protective of their females.

The Gibbons live in different parts of southeast Asia, from Burma, North Sumatra, and China to the Malay peninsula.  They dwell in branches and actually do not make nests.  Instead, they huddle with other gibbons or sleep alone.  Every morning, upon awakening, the gibbon uses a territorial hooting call, which is usually started by an adult female and last about a 1/2 hour.  The Gibbon does not show sexual dimorphism in size but it does show it in color.  Males usually have a coarse black fur and black skin with white fur on their cheeks, while the females are a golden or reddish color with black faces.  They are very distinguishable between each other.

Chimpanzees usually live in rain forests and wet savannas.  They spend most of their feeding and sleeping time in trees, yet they spend equal time on both land and trees.  The chimpanzee is very intelligent and social and is the mammal that is most like a human.  They have no tail surprisingly and they have short legs with long arms.  Most of their body is covered in hair, except their ears, face, fingers, and toes.  The females and male coloration are very similar, but they do differentiate in size greatly!  The females are usually 2-3 ft tall while the males range about 3-4 ft.

The environment seems to have a great deal of expression on the physical and behavioral traits of these 5 primates.  Gibbons, lemurs, and spider monkeys are very moveable and quick in their trees and canopies they live in.  Chimpanzees and Baboons are very quick witted and intelligent, living on the ground near humans and being exposed to villages.


  1. Wonderful discussion on sexual dimorphism, which is a favorite focus of study for me. I was expecting a discussion on diet, however. :-) (D-H last names were assigned "diet".)

    Other than that issue, the information was thorough and very well-written.

  2. very informational. wonderful job. Didn't know that gibbons huddle with one another but sleep alone. Nice fact!!!

  3. Oops I misread the assignment! I thought it said the first letter in your first name, "S". I'm kind of glad I misread it because the topic I wrote about was really interesting.