Philippine tarsiers: Not world's smallest primates, not marsupials

BBC's Meeting the world's smallest primate (click link for the site and video), is being criticized for its inaccurate information.  Made as an educational piece to show that the animal's popularity with tourists is affecting the animals' welfare, poor research and possibly bad editing culminated in some errors. While these errors are minute, they affect the overall educational purpose of this video. 

A Philippine tarsier (T. syrichta)

The show's host referred to Philippines tarsiers (Tarsius syrichta) as marsupials. T. syrichta (and all tarsiers for that matter) do not have marsupium, the hallmark of marsupials. Tarsiers are primates, grouped in the suborder of Haplorrhini. Tarsier offspring are born precocial, while marsupial offspring (joey) are born altricial. 

A baby tarsier with its mother. Tarsier offspring are born precocial.

Precocial offspring are relatively mature and mobile after birth. There is a distinct slowing down in brain growth relative to body growth at around time of birth. Altricial offspring on the other hand are born helpless. Their brain growth declines during the developmental stage instead of around the time of birth. Human babies are unique within primates because they are born "secondarily altricial" (Martin, 2007). While human offspring are born helpless, their brain growth relative to body growth continues for about a year before slowing down. Calling tarsiers marsupials is just rude (don't we all want to be primates?).

The claim that Philippines tarsiers is the smallest primate is also false. The title for the smallest primate actually goes to Berthe's mouse lemur (Microcebus berthae) (Dammhahn & Kappeler, 2005). 

A Berthe's mouse lemur (M. berthae).

Male Philippines tarsiers weigh 119-153 g (4.2-5.4 oz) and females weigh 110-132 g (3.9-4.7 oz) (Gron, 2008). Philippines tarsiers exhibit sexual dimorphism, where males are slightly heavier than females. Berthe's mouse lemur weigh 30.6 g (1.1 oz) for both males and females (Gron, 2009). Clearly, Philippines tarsiers weigh more than Berthe's mouse lemur.


Philippines tarsiers have a  head and body length of 11.7-12.7 cm (4.6-5.0 in) for both males and females (Gron, 2008). Berthe's mouse lemur have a head and body length of 9.2 cm (3.6 in) for both males and females (Gron, 2009). Clearly, Philippines tarsiers is longer in size than Berthe's mouse lemur. 


Also read Bonn Aure's BBC’s Faulty Tarsier Video on Time Travelling for his take on this video.

References:

Dammhahn, M. Kappeler, PM. 2005. Social System of Microcebus berthae , the World’s Smallest Primate. International Journal of Primatology 407-435. Retrieved May 08, 2010 http://www.springerlink.com/content/u6u4372474318166/

Gron, K. 2008. Primate Factsheets: Tarsier (Tarsius). Primate Info Net Retrieved May 08, 2010 http://pin.primate.wisc.edu/factsheets/entry/tarsier

Gron, K. 2009. Primate Factsheets: Mouse lemur (Microcebus). Primate Info Net Retrieved May 08, 2010 http://pin.primate.wisc.edu/factsheets/entry/mouse_lemur


Martin, RD. 2007. The evolution of human reproduction: a primatological perspective. American Journal of Physical Anthropology 45:59-84. Retrieved May 08, 2010 http://www.ncbi.nlm.nih.gov/sites/entrez?cmd=PureSearch&db=pubmed&term=18046752[UID]

When Is A Monkey Really A Monkey?

A little boy pressed his nose on the glass where a Western Lowland Gorilla is interacting with the zoo-goers. He turns around to his parents with a big smile. “Oh look, the monkey wants to kiss you”, said his mother.

At the lemur exhibit, a girl asks her parents what those black and white primates were. Her dad picks her up and said, “It’s a monkey, sweetie … let’s go”.

A pair of gibbons gracefully swings around in their exhibit. Excited, a group of kindergarteners cheered as these gibbons maneuver around its habitat with great agility. “These monkeys are so active”, said the teacher.

If this sounds familiar to you then you are not alone. I spent a great deal of time near primate exhibits mainly because I love to observe their behaviors. I also enjoy watching interaction between humans and primates. However, there are times when I just can’t control myself and felt compelled to walk over to these people and explain to them that the word “monkey” is not a general term for primates (politely, of course). It shocks me that most of the time people do not read the information panel at the exhibit (aren’t zoo trips for educational purposes?). So when is a monkey really a monkey?

Monkey is a colloquial term for any cercopithecoids (Old World monkey) and platyrrhines (New World monkey). Monkeys are not hominoids (apes) or prosimians. One of the most distinctive characteristic that differentiate monkeys and apes is the presence of a tail in monkeys. Gibbons, siamangs, orangutans, gorilla, chimpanzees and bonobos are apes because they do not have a tail.

Gorillas do not have tails, so they are not monkeys but apes.

Differentiating monkeys and prosimians are a little tricky; all prosimians have grooming claws (toilet claws) but it is generally not visible within zoo exhibits. Prosimians include lemurs, lorises, galagos, aye-ayes and tarsiers.

A ring-tailed lemur is a prosimian. Although it has a tail, it also have grooming claws so lemurs are not monkeys.

A hamadryas baboon is technically a monkey because it has a tail but has no grooming claws.

The Barbary Macaque, Macaca sylvanus, was formerly named Barbary Ape due to the absence of a tail (to be more precise, they have a vestigial tail that looks like a stump). However, we know now that it is more closely related to macaques than to apes so its name was changed to correctly reflect what they are.

A Barbary Ape (notice the lack of tail). Flickr photo from Gerald Davison.

This brings us back to the question, “when is a monkey really a monkey’? The most straightforward answer would be “when it has a tail but doesn’t have grooming claws”. However, the most convenient answer usually lies in front of you … on the information panel.

Flickr photo taken by tim ellis at the Twycross Zoo, England.
The sign reads "Who are you calling a monkey?"

First Ever Malaysian Tarsier Study Begins in Sabah.

Photo from Erwin Bolwidt (El Rabbit) on Flickr.com

At the Danau Girang Field Center, Lower Kinabatangan Wildlife Sanctuary, a young male tarsier named Jamil was tagged with a small radio collar as part of the first study to better understand the life of this elusive nocturnal primate species.

Dr. Benoit Goossens, the director of Danau Girang Field Center said there was a need for better understanding of habitat needs, diet and social organisation of tarsiers, key to conservation policies for these unique little creatures.

Read about the article from The Star here: First tarsier study begins.