Educated Guesses
Physical adaptations


Nonhuman primates are incredibly diverse in size, shape, type, and the ways that they are “outfitted” to be successful in their ecosystems. We witness this in the forms of the physical adaptations that Mother Nature bestowed upon them. Let’s explore WHY they have developed these adaptations and HOW they benefit the primate species and their ecosystems.

While doing this, you will learn about a variety of species and their habitats. You will learn why their bodies are designed for those habitats. You will see why these species need to be protected and their habitats preserved. Nonhuman primates are an indicator species of the health of their ecosystems. If they are at risk, so too is every species with whom they share their habitats. What will you discover?



Watch the video for the topic of your choice or the topic that your instructor selected for you.

Use the 5-Step Scientific method, illustrated below, to develop your educated guess.

You might develop a hypothesis early on. Why have you arrived at this hypothesis? After you do your research, you might change your mind. If so, why? Justify your conclusion.

Research carefully via your preferred search engine. Pose your search questions carefully. In some cases, we provide hints for the types of questions or topics to search for.

Do not rely solely on the initial answers that pop up. Sometimes the internet lists choices because they are based on the authors’ opinions. But will their opinions be your opinions? Search further until you are satisfied that you have the full “picture.”

After you do your internet searches, come back to our Primate Species Profiles to learn more about the species in question.

You’ll find some hints in our videos. But you have to figure out the value of those hints for yourself. Some may lead you slightly astray to encourage you to research more carefully. And don’t just look up the species in the videos. There are over 500 fascinating primate species to choose from. You may meet some that you’ve never before heard of. 

Identifying Species by Name

When you name a species, be aware that it might have multiple common names. In some very confusing cases, some species even share common names! Make sure that you’re being as specific as possible. 

What happens when species have multiple common names or share common names? Scientific names, which are written in Latin, clear up the confusion. Click the button to the left below to find out why species have both common names and scientific names. Click the button on the right, below, to learn how species’ names are written.


Common names are not officially defined. They are based on everyday conversational language and may differ by country, region, profession, community, or other factors. As a result, it is not unusual for a species to have more than one common name.

Scientific names are in Latin and they are written in italics. They are standardized and for everyone, no matter what language you may speak. They are bound by a formal naming system, called binominal nomenclature, that has strict rules. Scientific names prevent misidentification. Those names only change if a species, or its genus, is officially redesignated by experts.


Naming living organisms is called "binominal nomenclature."

Common names are generally not capitalized, except as required because they include a person's name or a place, or because the name starts a sentence. If the name does not include a person or place, it will look like these examples:

ring-tailed lemur, common woolly monkey, or rhesus macaque.

If parts of the common name are based on a place or person's name, it might look like these examples:

Delacour's langur (person), Mt. Kilimanjaro guereza (place), or Barbary macaque (place)

Scientific names have very specific rules. First, there are two parts to the name: the genus and the species. Second, both parts of the name are italicized. And third, only the genus name is capitalized, even if the species name is a person or a place.

Example: the scientific name for the ring-tailed lemur is Lemur catta, the common woolly monkey is Lagothrix lagotricha, and the rhesus macaque is Macaca mulatta.

If the species name includes a place or person, that portion of the is still NOT capitalized since it's the species.

Example: The Delacour's langur is named for Jean Théodore Delacour, the first western scientist to encounter the species. Its scientific name is Trachypithecus delacouri. The Latinized version of Delacour is "delacouri" and it is NOT capitalized. 

The exception to these rules (and there are always exceptions) is if you're naming a subspecies. Then there are three parts to the name: the genus (capitalized), the species (not capitalized), and the subspecies (not capitalized). All are italicized:

Example: The western lowland gorilla, Gorilla gorilla gorilla, is a subspecies of the western gorilla, Gorilla gorilla

For some of the exercises in this lesson, you may need to name the subspecies too, especially for great apes. For help with this, go to the Primate Species Profiles dropdown menu. For others, you don’t need to get too deeply into the species’ name. You can just list the primate family, for example, “squirrel monkey,” “guenon,” or “gibbon.” The lesson overview will tell you how detailed you should get. 

For all primate species, include in your hypothesis where they live. Name the continent, country or countries, and habitat type or types. This is a very important part of determining why they have evolved these adaptations. Remember, the physical adaptations are meant to enable the primate species to have the greatest success in and for their natural habitat or habitats. (Hint: some primates live in multiple habitat types.)

Conservation Statuses

Be sure to keep an eye out for the species’ Conservation Status. Is the species threatened or endangered? If they are built for success, why are they threatened or endangered?


1. Consider the Question or Questions in the Videos

2. Make Observations

3. Form Your hypothesis

    1. What’s your initial guess based on your observations?

4. Gather Data

    1. This is the research step
    2. Learn about the species in your hypothesis

5. Analyze Your Data and Draw Your Conclusion or Conclusions

    1. Test your hypothesis against what you learn
    2. Have you changed your mind? If so, why? If not, why?

Who are the largest and the smallest apes, monkeys, and prosimians?

Why are some giants and others as small as a mouse?

What is the ecological niche that they support? 

Click here to learn the difference between apes, monkeys, and prosimians.

Which PRIMATE is the largest? Which is the smallest? 

This is about ALL primates including apes, monkeys, and prosimians.

The answers may or may not be in the video, but there are surely hints.

For comparison photos, go to the Primates At-a-Glance dropdown menu or the genus pages from the Primate Species Profiles dropdown menu. We’ll guide you to where to find them below.


In this list of the primates feature in the "Largest and Smallest Primates" video, we show you the common and scientific names so you can see what they look like. It's up to you or your instructor to determine if you should deliver the common names only or both the common and scientific names.

We also show you where you can find the species in the Primate Species Profiles dropdown menu.

  • Western lowland gorilla (Gorilla gorilla gorilla)
    • Find in  "Apes of Africa"
  • Bornean orangutan (Pongo pygmaeus)
    • Find in "Apes of Asia"
  • Grauer's gorilla (Gorilla beringei graueri)
    • Find in "Apes of Africa"
  • Bornean orangutan (Pongo pygmaeus)
    • Find in "Apes of Asia"
  • Silvery marmoset (Mico argentatus)
    • "Find in "Monkeys of Latin America"
  • Horsfield's tarsier (Cephalopachus bancanus)
    • "Find in "Prosimians of Asia"
  • Madame Berthe's mouse lemur (Microcebus berthae)
    • Find in "Prosimians of Africa/Lemurs" (There are so many lemur species, we gave them their own dropdown menu)
  • Andean night monkey (Aotus miconax)
    • Find in "Monkeys of Latin America"

Who are the largest and smallest monkeys? This is an opportunity to understand that all monkeys are primates, but not all primates are monkeys. Monkeys are very diverse. Where do they live? How do they live? Why are some very large and some very small?

Which MONKEY species is the largest? Which is the smallest? 

This is about monkeys and does not include apes and prosimians.

The answers may or may not be in the video, but there are surely hints.

For photos to compare monkey sizes, go to the Primates At-a-Glance monkeys pages and/or monkey genus pages from the Primate Species Profiles dropdown menu. We’ll guide you to where to find them below.


In this list, we also show you where you can find the species listed in the Primate Species Profiles dropdown menu.

If you'd like to see how to identify them with both common and scientific names, click on the button for the list of primates featured in the "Largest and Smallest Primate" video for examples. 

  • Drill
  • Mandrill
  • Mandrill, male and female
    • Find all above in "Monkeys of Africa"
  • Black-tailed marmoset
  • Pygmy marmoset
    • Find them in "Monkeys of Latin America"
  • Gray-cheeked mangabey
    • Find in "Monkeys of Africa"
  • Black lion tamarin
  • Emperor tamarin
    • Find them in "Monkeys of Latin America"

Among monkey genera (plural of “genus”), there are some pretty wacky-looking noses.

Which species has the most unusual-looking largest nose and the most unusual-looking smallest nose?

Why? What’s the purpose of those unusual noses? How does this style of nose size set them up for success in their environment?

This exercise is about monkeys and does not include apes and prosimians. (All monkeys are primates, but not all primates are monkeys!)

The answers may or may not be in the video, but there are surely hints there.

For photos to compare, go to the Primates At-a-Glance monkeys pages and/or monkey genus pages from the Primate Species Profiles dropdown menu. Where’ll guide you to where to find them below.

To learn about the general differences in nose shapes between Afro-Eurasian monkeys and American monkeys, go to Primate Facts and scroll down to “New World and Old World Monkeys: What’s the Difference?”


These primates are listed by both their common and scientific names. It's up to you or your instructor whether you should identify the species with the most unusual noses by their common names or by both their common and scientific names.

We also show you where to find the species in the Primate Species Profiles dropdown menu.

  • Male proboscis monkey (Nasalis larvatus)
  • Female proboscis monkey (Nasalis larvatus)
    • Find them in "Monkeys of Asia"
  • Hamadryas baboon (Papio hamadryas)
    • Find him in "Monkeys of Africa"
  • Golden snub-nosed monkey (Rhinopithecus roxellana)
  • Yunnan snub-nosed monkey (Rhinopithecus bieti)
    • Find them in "Monkeys of Asia"
  • Collins' squirrel monkey (Saimiri collinsi)
    • Find in "Monkeys of Latin America"
  • Lowe's monkey (Cercopithecus lowei)
    • Find in "Monkeys of Africa" (Hint: he's a guenon)
  • Toque macaque (Macaca sinica)
    • Find in "Monkeys of Asia"

Speaking of noses, here’s something you’ve probably never thought about: some primates have dry noses (like us, for example) and some have wet noses (like dogs and cats have). That’s pretty interesting! Why would that be? And who has what kind of nose? How does the wetness or dryness of their noses benefit them? What does it tell you about their vision or hearing abilities? What does it tell you about how they live? What does it tell you about how they perceive their world and everything in it?

Which primates have dry noses? What have wet noses? And why? 

For this exercise, you don’t need to find the exact primate species. The common name for the family or genus is fine. 

So, for example, it’s not necessary to refer to chimpanzees as their genus “Pan.” “Chimpanzees” works. 

Another example, you don’t refer to tarsiers by their genus name “Tarsiidae.” “Tarsier” is fine. You also don’t need to note the exact species, like Philippine tarsier. The subject matter is generalized to the entire genus or family. This is because if a Philippine tarsier has a wet or dry nose, all tarsiers have the same.

Since primates having wet noses vs. dry noses is kind of an unusual category that most people may not realize is even a “thing,” we’re going to give you some hints.

The biological order “Primates” is divided into two groups or suborders:

  • Strepsirrhini or wet-nosed primates
  • Haplorhini or dry-nosed primates

What is a primate family vs. primate genus vs. primate species? See the chart below.

Click the button below to learn about the “biological order” of living organisms, including a diagram.


A biological order is one of the eight major hierarchical taxonomic ranks, which you can see in the diagram below.

Illustration: Peter Halasz/Creative Commons

What is "taxonomy"? Taxonomy is the naming and classifying of biological organisms.

Therefore, a "taxonomic rank" is a listing of biological classifications in a particular order determined by scientists.

In scientific classification, all primates are in the

  • in the Kingdom: "Animalia"
  • in the Phylum: "Chordata"
  • in the Class: "Mammalia"
  • in the Order: "Primates"
  • in the Suborder: "Haplorhini" or "Strepsirrhini"

After that comes their taxonomic "family" (there are even sometimes subfamilies), followed by their genus, and finally their species.


In this list of the primates featured in this "Wet Noses or Dry Noses" video, we note the last three indicators of their biological order: the family, genus, and species to which they belong. This should give you an idea of how the biological order "Primates" works. 

 What might this tell you about who would have wet noses and who would have dry noses? 

  •  Chimpanzee
    • Family: Hominidae
    • Genus: Pan
    • Species: Pan troglodytes
  • Wooly lemur
    • Family: Indriidae
    • Genus: Avahi
  • Tarsier
    • Family: Tarsiidae
    • Genus: 3 genera
  • Woolly monkey
    • Family: Atelidae
    • Genus: Lagothris
  • Potto
    • Family: Lorisidae
    • Genus: Perodicticus
  • Gibbon
    • Family: Hylobatidae
    • Genus: 4 genera
  • Langur
    • Family: Cercopithecidae
    • Subfamily: Colobinae
    • Genus: at least 5 genera
  • Galago
    • Family: Galagidae
    • Genus: 6 genera

Most nonhuman primates, even the smallest, have hands that pretty much look and act like ours. We’d be lost without our opposable thumbs. Most apes, monkeys, and prosimians have opposable thumbs. What are opposable thumbs? Do the research to find a clear definition. What are the benefits to having opposable thumbs? For primates, its one of they keys to our success and survival in our habitats.

Some primates do NOT have opposable thumbs. When might it NOT be beneficial for primates to have thumbs that oppose like ours? Think about the way some animals are built to move through their habitats. Might opposable thumbs get in the way? Do they need opposable thumbs?

When might it be beneficial to not have thumbs at all? Or to have thumbs so small they stay out of the way? Think about that!

Most nonhuman primates have flat fingernails (like ours). A few have claws or a combination of some fingers with claws and some with flat fingernails. Who? Why? What are the benefits?

Some have “grooming claws.” Why would they need that? Who are those primates?

Some primates have webbing between their fingers or toes! (Sometimes humans have webbed toes.) Why might they need themt? What is the benefit of webbed toes? How might it benefit certain primate species?

Hands down, the craziest primate hands go to the aye-aye (Daubentonis). Their wacky long middle fingers swivel due to a ball-and-socket joint. Aye-ayes use their middle fingers to forage for grubs in trees—tapping on the bark and listening for wood-boring insects moving around beneath it. Look it up. You’ll want to see this!

In the diagram below, you’ll find a wide variety of primate hands with an equally wide variety of shapes.

Here are some things to consider:

  • How do the primates live?
  • Where do they live? 
  • Are they arboreal or terrestrial or both?
  • How do they need to get around? How do they “locomote”?
  • Do they climb? How? Do they climb trees, or do they climb rugged rock-faced cliffs?
  • Do they leap? Different primates leap in different ways. How do they “take off”? How do they land? What hand shapes help them?
  • Do they swing when they climb? What’s the best hand shape for swinging through the forest?
  • Do they swim? Do they swim for pleasure or to escape predators?
  • What do they eat? What are the best means of accessing that food?

Hint: If you’d like to learn more about primate locomotion, go to “Lifestyle Adaptation” and visit the “Do the Locomotion: Modes of Travel” exercise. 

What other questions would you ask to determine the best hand shape for a primate species? Now, don’t just look up the primates in the video. There are over 500 primate species to choose from. Find others that you think are interesting and discover why their hands are shaped as they are.


The hands in the illustration are listed by the scientific (Latin) name for their genus.

(The first example in the illustration, "Taupaia," is a tree shrew, which is not a primate! We don't know why it's in the illustration, so please ignore it.)

Here are their common names:

Lemur is ring-tailed lemurs

Daubentonia is aye-ayes

Loris is slender lorises

Nycticebus is slow lorises

Perodicticus is pottos

Galago is galagos or bushbabies

Tarusus is tarsiers

Leontocebus is certain tamarin species

Aotus is night monkeys

Saimiri is squirrel monkeys

Cebus is capuchin monkeys

Ateles is spider monkeys

Macaca is macaques

Papio is baboons

Cercopithecus is guenons

Presbytis is langurs

Nasalis is proboscis monkeys

Colobus is colobus monkeys

Hylobates is gibbons

Pongo is orangutans

Pan is chimpanzees

Gorilla is, you guessed it, gorillas

Homo is humans

Almécija, Sergio & C Shwerwood, Chet. (2017). Hands, Brains, and Precision Grips: Origins of Tool Use Behaviors. 10.1016/B978-0-12-804042-3.00085-3.

In this list, beneath the name is the genus listed in the illustration that best visualizes the hands of each primate's genus.

  • Colombian white-throated capuchin
    • See the hand for Cebus
  • Bornean orangutan
    • See the hand for Pongo
  • Dusky langur
    • See the hand for Presbytus
  • Ornate spider monkey
    • See the hand for Ateles
  • Cotton-top tamarin
    • The hand for Leontocebus is the closest
  • Black and white ruffed lemur
    • The hand for Lemur is the closest
  • Zanzibar red colobus
    • That one's easy, see the hand for Colobus
  • Bonnet macaque
    • See the hand for Macaca
Copyright © New England Primate Conservancy 2023. You may freely use, copy and share these Learning Activities for educational purposes. 
For questions or comments, e-mail us at [email protected]