What is the Difference Between Strepsirhines and Haplorhines

The main difference between strepsirhines and haplorhines is that strepsirhines make up one of the two suborders of primates, containing wet-nosed primates, whereas haplorhines make up the second suborder, containing dry-nosed primates. Strepsirhines include lemurs, galagos, pottos, and lorises while haplorhines include tarsier, monkey, apes, and humans. Moreover, strepsirhines are lower primates while haplorhines are higher primates. 

Strepsirhines and haplorhines are the two suborders of primates. Generally, primates are eutherian mammals with characteristic adaptations to their challenging environment. Some of these adaptations include large brains, visual acuity, colour vision, altered shoulder girdle, and dexterous hands.  

Key Areas Covered 

1. Strepsirhines
     – Taxonomy, Characteristics
2. Haplorhines
     – Taxonomy, Characteristics
3. What are the Similarities Between Strepsirhines and Haplorhines
     – Outline of Common Features
4. What is the Difference Between Strepsirhines and Haplohines
     – Comparison of Key Differences

Key Terms 

Haplorhines, Lemuriformes, Lorisiformes, Primates, Simiiformes, Strepsirhines

Strepsirhines – Taxonomy, Characteristics 

Strepsirhines are the lower primates, belonging to the suborder Strepsirhini. The main characteristic feature of strepsirhines is the presence of a wet nose.  

Taxonomy 

Generally, there are three suborders of the suborder Strepsirhini. They are the Infraorder Adapiformes, Lemuriformes, and Lorisiformes. Here, the infraorder Adapiformes have extinct members. However, the two infraorders – Lemuriformes and Lorisiformes – include extant members.

Figure 1: Gray Slender Loris (Loris lydekkerianus nordicus)

Basically, lemuriforms include lemurs of Madagascar, galagos, and pottos from Africa. On the other hand, lorisiforms include the lorises from India and Southeast Asia.  

Characteristics 

Furthermore, strepsirhines have small brains in comparison to their body size. Their brains also have large olfactory lobes, which give an increased sense of smell. In addition, they can sense pheromones through their vomeronasal organ. They have an increased night vision due to the presence of a reflective layer. Meanwhile, lemuriforms have a toothcomb, a specialized set of teeth in the front, lower part of the mouth mostly used for combing fur during grooming.  

Haplorhines – Taxonomy, Characteristics 

Haplorhines are the higher primates belonging to the suborder Haplorhines. They can be identified as dry-nosed primates.  

Taxonomy 

Generally, the suborder Haplorhines includes two infraorders: infraorder Tarsiiformes and infraorder Simiiformes. Here, the infraorder Tarsiiformes contains the family Tarsiidae including tarsiers that are prosimians.  

Figure 2: Emperor Tamarin (Saguinus imperator)

On the other hand, the infraorder Simiiformes include simians, monkeys, apes, and humans. However, it includes two parvorders: Platyrrhini, including New World monkeys, and Catarrhini including Old World anthropoids.

Figure 3: Common Squirrel Monkey (Saimiri sciureus)

Furthermore, the parvorder Catarrhini includes two superfamilies: Cercopithecoidea including Old World Monkeys, and Hominidea including apes and humans. Moreover, there are two taxonomic groups of apes. They include the family Hylobatidae including lesser apes (gibbons) and the family Hominidae including the greater apes and humans. Great apes include orangutans, gorillas, and chimpanzees. On the other hand, humans belong to the genus Homo. 

Characteristics 

The ancestral rhinarium (the tip of the snout) found in strepsirrhines is replaced by the upper lip of haplorhines. Therefore, their upper lip is not directly connected to the gum or to the nose. Significantly, this allows for a large range of facial expressions. Furthermore, haplorhines have a high brain-to-body mass ratio. Their primary sense is vision. Moreover, tarsiers have a bicornate uterus, the same as the strepsirrhines. Meanwhile, anthropoids have a single-chambered uterus. All primates have a similar gestation period although the newborns of haplorhines are larger in size. 

Similarities Between Strepsirhines and Haplorhines 

• Strepsirhines and haplorhines are the two suborders of primates. 
• They are eutherian mammals that arose 85–55 million years ago from terrestrial mammals (Primatomorpha). 
• Moreover, they adapted to live in the tree of tropical forests with characteristic adaptations to their challenging environment. These adaptations include large brains, visual acuity, colour vision, altered shoulder girdle, and dexterous hands.  
• They have four limbs – a pair of legs and a pair of arms with altered shoulder girdle, including clavicles. In addition, the lower limb has two separate bones which are highly mobile; radius and ulna in the lower forelimbs and tibia and fibula in the lower hindlimbs. 
• They have opposable thumbs and, except for humans, opposable large toes, assisting in grasping and manipulation behaviours of their arboreal lifestyle.  
• Moreover, their dexterous fingers have flat nails for at least one digit. Fingers and toes also have fingerprints.  
• Their body is covered with short, dense hair, except for the face. 
• In addition, they have flat faces with small snouts and small ears. 
• They have reduced olfactory sensation, but mainly rely on the visual sensation.  
• Furthermore, they have bony orbital eye rings and an outgrowth of the petrosal bone, enclosing the middle ear. 
• Their eyes are forward-facing with visual acuity, colour vision, and binocular vision.  
• Not only that, their brains are relatively large and complex with higher intellectual abilities. 
• They have a reduced number of teeth, with a maximum of two incisors, one canine, three premolars, and three molars in each jaw quadrant.  
• Moreover, their gestation time is long, with an extended period of juvenile growth and period of maternal investment and care.  
• They are omnivores, consuming small invertebrates, fruits, and plants. 

Difference Between Strepsirhines and Haplohines 

Definition 

Strepsirhines refer to a suborder of primates, including the lemuriform primates that characteristically have a moist area around the nostrils, while haplorhines refer to the second suborder of primates, including New World monkeys, Old World monkeys, and apes.  

Also Known as 

Strepsirhines are also known as wet-nosed primates while haplorhines are also known as dry-nosed primates. 

Classification 

The infraorders of Strepsirhines are the Adapiformes, Lemuriformes, and Lorisiformes while the infraorders of haplorhines are the Tarsiiformes and Simiiformes. 

Organization 

While strepsirhines are lower primates, haplorhines are higher primates. 

Habitat 

Many strepsirhines are arboreal while haplorhines can be either arboreal or terrestrial. 

Brain Size 

Strepsirhines have a smaller brain size while haplorhines have comparatively large brains. 

Skull 

Moreover, strepsirhines have no plate separating orbit from temporal fossa while haplorhines have a plate separating orbit from temporal fossa. 

Toothcomb 

Strepsirhines have lower incisors forming a toothcomb while haplorhines do not have a toothcomb. 

Facial Features 

Strepsirhines have longer snouts while haplorhines have short faces. 

Nose 

Another difference between strepsirhines and haplohines is their nose. Strepsirhines have naked noses while haplorhines have furry noses. 

Senses 

Strepsirhines have a highly developed sense of smell while haplorhines have a highly developed sense of vision. 

Eyes 

Moreover, strepsirhines have less forward-facing eyes while the eyes of haplorhines are more forward-facing. 

Production of Vitamin C 

Strepsirihines can produce their own vitamin C while haplorhines are unable to produce their own vitamin C. 

Examples 

Furthermore, strepsirhines include lemurs, galagos, pottos, and lorises while haplorhines include tarsier, monkey, apes, and humans. 

Conclusion 

Strepsirhines are one of the two suborders of primates, consisting of wet-nosed primates such as lemurs, galagos, and lorisids. They are mainly arboreal. They have a toothcomb and small brains. On the other hand, haplorhines are the second suborder of primates, including tarsier, monkeys, apes, and humans. Significantly, they have a large brain size in comparison to their body size and rely on vision rather than smell as strepsirhines. Therefore, the main difference between strepsirhines and haplohines is their general characteristics. 

References:

1. “SUBORDER STREPSIRHINI.” Natural History Collections, UNIVERSITY OF EDINBURGH, Available Here.
2. “SUBORDER HAPLORHINI.” Natural History Collections, UNIVERSITY OF EDINBURGH, Available Here.

Image Courtesy:

1. “Loris lydekkerianus nordicus 003” By Dr. K.A.I. Nekaris – email (CC BY-SA 4.0) via Commons Wikimedia    
2. “Tamarin portrait 2 edit3” By Brocken Inaglory, edited by Fir0002, edited by Brocken Inaglory – Own work (CC BY-SA 4.0) via Commons Wikimedia   
3. “Totenkopfaeffchen” (CC BY-SA 2.0 de) via Commons Wikimedia