What is the Difference Between Strepsirrhini and Haplorhini

The main difference between Strepsirrhini and Haplorhini is that Strepsirrhini contains lower primates, mainly lemuriform primates, whereas Haplorhini contains higher primates including New World monkeys, Old World monkeys, and apes. Furthermore, strepsirrhines have naked noses, lower incisors forming a toothcomb, and no plate separating orbit from temporal fossa while haplorhines have furry noses and a plate separating orbit from temporal fossa, and they lack a toothcomb.

Strepsirrhini and Haplorhini are the two suborders of primates, which are developed and intelligent group of mammals, typically having flexible hands and feet with opposable first digits and good eyesight.

Key Areas Covered

1. Strepsirrhini
     – Definition, Characteristics, Behavior
2. Haplorhini
     – Definition, Characteristics, Behavior
3. What are the Similarities Between Strepsirrhini and Haplorhini
     – Outline of Common Features
4. What is the Difference Between Strepsirrhini and Haplorhini
     – Comparison of Key Differences

Key Terms

Haplorhini, New World Monkeys, Old World Monkeys, Primates, Strepsirrhini, Teeth, Toothcomb

Strepsirrhini – Definition, Characteristics

Strepsirrhini is one of the two suborders of primates. And, this order especially contains lower primates. The two infraorders of Strepsirrhini are Lemuriformes and Lorisiformes. Here, the infraorder Lemuriformes includes lemuriform primates, consisting of the lemurs of Madagascar, galagos (“bushbabies”) and pottos from Africa. On the other hand, the infraorder Lorisiformes includes the lorises from India and Southeast Asia. Moreover, the extinct adapiform primates belong to this suborder.

Figure 1: Gray Slender Loris

Furthermore, the main characteristic feature of strepsirrhines their “wet” (moist) rhinarium (the tip of the snout). Therefore, they are also known as wet-nosed animals. Lower incisors forming a toothcomb and the lack of a plate separating orbit from temporal fossa are other significant features. Moreover, the second digit on the hind foot of many of them is modified to form a “toilet claw” used in grooming. However, most strepsirrhines are arboreal species. They have a small brain size when compared to the other primates.

Haplorhini – Definition, Characteristics

Haplorhini is the second suborder of primates. And, this suborder mainly contains higher primates. The three suborders of the order Haplorhini are the Tarsiiformes, Platyrrhini, and Catarrhini. Tarsiiformes live in Europe, northern Africa, Asia, and North America but, they include some extant species that lived in the islands of Southeast Asia. Also, the infraorder Platyrrhini includes New World monkeys while the infraorder Catarrhini includes both Old World monkey and apes.

Figure 2: Ne World Monkey (Brown Spider Monkey)

Moreover, the main characteristic features of Haplorhines include the furry nose and a plate separating orbit from temporal fossa. However, they lack a toothcomb. Also, platyrrhines have a flat nose with outwardly directed nasal openings. Additionally, they have three premolars in upper and lower jaws, anterior upper molars. The two families of platyrrhines are Cebidae and Callitrichidae. Catarrhines have paired downwardly directed nasal openings, which are close together. However, they usually have two premolars in each jaw, anterior upper molars. The three families of catarrhines include Cercopithecidae, Hylobatidae, Hominidae.

Similarities Between Strepsirrhini and Haplorhini

• Strepsirrhini and Haplorhini are the two suborders of primates.
• They are placental mammals.
• They live in the tropics or subtropics.
• Except for a few terrestrial species, they are arboreal. Some species eat leaves or fruit; others are insectivorous or carnivorous.
• Furthermore, both have an opposable thumb and big toe as an adaptation to an arboreal lifestyle, assisting in grasping and manipulation behaviors.
• Also, they have flat nails instead of claws, with dermatoglyphs (fingerprints) on fingers and toes.
• They show hind limb-dominated locomotion.
• They have unfused and highly mobile radius and ulna in the forelimb and tibia and fibula in the hind limb.
• Moreover, they have pentadactyl feet a clavicle.
• However, they show a relative reduced olfactory sensory system (smaller snouts) when compared to other mammals.
• They also have increased reliance on visual sensation.
• Their eyes are large and exhibit a high degree of frontation, or placement toward the front of the face, increasing the overlap of visual fields, increasing binocular vision. Therefore, each eye sends visual information to both hemispheres of the brain, enhancing depth perception and producing stereoscopic vision.
• They have longer gestation times, and extended period of juvenile growth with an increased period of maternal investment and care.
• Significantly, they have relatively large brains.
• Besides, they have a reduced number of teeth, with a maximum of two incisors, one canine, three premolars, and three molars in each jaw quadrant.

Difference Between Strepsirrhini and Haplorhini

Definition

Strepsirrhini refers to a suborder of primates that includes the lemuriform primates that characteristically have a moist area around the nostrils while Haplorhini refers to the second suborder of primates including New World monkeys, Old World monkeys, and apes. Thus, this is the main difference between Strepsirrhini and Haplorhini.

Organization

While Strepsirrhines are lower primates, haplorhines are higher primates.

Habitat

Also, many strepsirrhines are arboreal while haplorhines can be either arboreal or terrestrial.

Brain Size

Besides, brain size is also a difference between Strepsirrhini and Haplorhini. Strepsirrhines have a smaller brain size while haplorhines have comparatively large brains.

Characteristics

Moreover, strepsirrhines have naked noses, lower incisors forming a toothcomb, and no plate separating orbit from temporal fossa while haplorhines have furry noses and a plate separating orbit from temporal fossa, and they lack a toothcomb. Hence, this is the difference between Strepsirrhini and Haplorhini in terms of their characteristics.

Infraorders

Furthermore, the two infraorders of Strepsirrhini are the Lemuriformes and Lorisiformes while the infraorders of Haplorhini are the Tarsiiformes, Platyrrhini, and Catarrhini.

Conclusion

Strepsirrhini is a suborder containing lower primates including the lemuriform primates. The main characteristic feature of them is the presence of a moist nose. On the other hand, Haplorhini is the second suborder, containing higher primates including New World monkeys, Old World monkeys, and apes. Haplorhines contain a furry nose. However, the main difference between Strepsirrhini and Haplorhini is their distinct characteristics.

References:

1. “Order Primates.” PRIMATES, Available Here.

Image Courtesy:

1. “Loris lydekkerianus nordicus 003” By Dr. K.A.I. Nekaris (CC BY-SA 4.0) via Commons Wikimedia   
2. “BrownSpiderMonkey (edit2)” By http://www.birdphotos.com edit by Fir0002 – Image:BrownSpiderMonkey.jpg, (CC BY-SA 3.0) via Commons Wikimedia