Pygmy Marmoset
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Pygmy marmosets are two
species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...
of small
New World monkey New World monkeys are the five families of primates that are found in the tropical regions of Mexico, Central and South America: Callitrichidae, Cebidae, Aotidae, Pitheciidae, and Atelidae. The five families are ranked together as the Ceboi ...
s in the genus ''Cebuella''. They are native to
rainforests Rainforests are forests characterized by a closed and continuous tree Canopy (biology), canopy, moisture-dependent vegetation, the presence of epiphytes and lianas and the absence of wildfire. Rainforests can be generally classified as tropi ...
of the western
Amazon Basin The Amazon basin is the part of South America drained by the Amazon River and its tributary, tributaries. The Amazon drainage basin covers an area of about , or about 35.5 percent of the South American continent. It is located in the countries ...
in South America. These primates are notable for being the smallest monkeys in the world, at just over . They are generally found in
evergreen In botany, an evergreen is a plant which has Leaf, foliage that remains green and functional throughout the year. This contrasts with deciduous plants, which lose their foliage completely during the winter or dry season. Consisting of many diffe ...
and river-edge forests and are gum-feeding specialists, or gummivores. About 83% of the pygmy marmoset population lives in stable troops of two to nine individuals, including a dominant male, a breeding female, and up to four successive litters of offspring. The modal size of a standard stable troop would be six individuals. Although most groups consist of family members, some may also include one or two additional adult members. Members of the group communicate using a complex system including vocal, chemical, and visual signals. Three main calling signals depend on the distance the call needs to travel. These monkeys may also make visual displays when threatened or to show dominance. Chemical signaling using secretions from glands on the chest and genital area allow the female to indicate to the male when she is able to reproduce. The female gives birth to twins twice a year and the
parental care Parental care is a behavioural and evolutionary strategy adopted by some animals, involving a parental investment being made to the evolutionary fitness of offspring. Patterns of parental care are widespread and highly diverse across the animal k ...
is shared among the group. The pygmy marmoset has been viewed as somewhat different from typical
marmoset The marmosets (), also known as zaris or sagoin, are twenty-two New World monkey species of the genera '' Callithrix'', '' Cebuella'', '' Callibella'', and ''Mico''. All four genera are part of the biological family Callitrichidae. The term ...
s, most of which are classified in the genera ''
Callithrix ''Callithrix'' is a genus of New World monkeys of the family Callitrichidae, the family containing marmosets and tamarins. The genus contains the Atlantic Forest marmosets. The name ''Callithrix'' is derived from the Greek words ''kallos'', ...
'' (where they were placed in a subgenus) and ''
Mico Mico may refer to: People * Mićo Janić (born 1979), Croatian sprint canoer * Mićo Ljubibratić (1839–1889), Serbian revolutionary * Mico Palanca (1978–2019), Filipino actor * Mićo Smiljanić (born 1974), Serbian/Montenegrin footballer * Mi ...
'', and thus is accorded its own genus, ''Cebuella'', within the family
Callitrichidae The Callitrichidae (also called Arctopitheci or Hapalidae) are a family of New World monkeys, including marmosets, tamarins, and lion tamarins. At times, this group of animals has been regarded as a subfamily, called the Callitrichinae, of th ...
. Their biggest threats are
habitat loss Habitat destruction (also termed habitat loss or habitat reduction) occurs when a natural habitat is no longer able to support its native species. The organisms once living there have either moved elsewhere, or are dead, leading to a decrease ...
and the
pet trade Wildlife trade refers to the exchange of products derived from non-domesticated animals or plants usually extracted from their natural environment or raised under controlled conditions. It can involve the trade of living or dead individuals, tis ...
.


Evolution and taxonomy

Debate has arisen among primatologists concerning the proper genus in which to place the pygmy marmoset. An examination of the interstitial
retinol binding protein Retinol-binding proteins (RBP) are a family of proteins with diverse functions. They are carrier proteins that bind retinol. Assessment of retinol-binding protein is used to determine visceral protein mass in health-related nutritional studies. R ...
nuclear gene (''IRBP'') in three marmoset species showed that ''
Callithrix ''Callithrix'' is a genus of New World monkeys of the family Callitrichidae, the family containing marmosets and tamarins. The genus contains the Atlantic Forest marmosets. The name ''Callithrix'' is derived from the Greek words ''kallos'', ...
'' as constructed in the 1990s also needed to include ''C. pygmaea'' to be
monophyletic In biological cladistics for the classification of organisms, monophyly is the condition of a taxonomic grouping being a clade – that is, a grouping of organisms which meets these criteria: # the grouping contains its own most recent co ...
, and that the times of separation of ''pygmaea'' and the ''argentata'' and ''jacchus'' species groups from one another are less than 5 million years ago, as might be expected for species of the same genus. However, subsequent separation of the ''argentata'' and ''jacchus'' species groups into different genera (the ''argentata'' group having been moved to ''Mico'') justifies maintaining a separate genus for the pygmy marmosets, as ''Callithrix'' is no longer
paraphyletic Paraphyly is a taxonomic term describing a grouping that consists of the grouping's last common ancestor and some but not all of its descendant lineages. The grouping is said to be paraphyletic ''with respect to'' the excluded subgroups. In co ...
. The two species described of the pygmy marmoset are: Few morphological differences occur between these species, as they may differ only slightly in color, and they are separated only by geographical barriers, including large rivers in South America. The evolution of this genus diverged in terms of body mass from typical primates, with a high rate of body-mass reduction. This involves large decreases in prenatal and postnatal growth rates, furthering the thought that progenesis played a role in the evolution of this animal.


Physical description

Pygmy marmosets are the smallest true monkey, with a head-body length ranging from and a tail of . The average adult body weight is just over with the only sexual dimorphism of females being a little heavier. The fur colour is a mixture of brownish-gold, grey, and black on its back and head and yellow, orange, and tawny on its underparts. Its tail has black rings and its face has flecks of white on its cheeks and a white vertical line between its eyes. It has many adaptations for
arboreal Arboreal locomotion is the locomotion of animals in trees. In habitats in which trees are present, animals have evolved to move in them. Some animals may scale trees only occasionally (scansorial), but others are exclusively arboreal. The hab ...
living, including the ability to rotate its head 180° and sharp, claw-like nails used to cling to branches and trunks of trees. Its dental morphology is adapted to feeding on gum, with specialised incisors that are used to gouge trees and stimulate
sap Sap is a fluid transported in the xylem cells (vessel elements or tracheids) or phloem sieve tube elements of a plant. These cells transport water and nutrients throughout the plant. Sap is distinct from latex, resin, or cell sap; it is a s ...
flow. The
cecum The cecum ( caecum, ; plural ceca or caeca, ) is a pouch within the peritoneum that is considered to be the beginning of the large intestine. It is typically located on the right side of the body (the same side of the body as the appendix (a ...
is larger than usual to allow for the greater time gum needs to break down in the stomach. Pygmy marmosets walk on all four limbs and can leap up to between branches.


Ecology


Geographic range and habitat

Pygmy marmosets can be found in much of the western
Amazon Basin The Amazon basin is the part of South America drained by the Amazon River and its tributary, tributaries. The Amazon drainage basin covers an area of about , or about 35.5 percent of the South American continent. It is located in the countries ...
, in
Brazil Brazil, officially the Federative Republic of Brazil, is the largest country in South America. It is the world's List of countries and dependencies by area, fifth-largest country by area and the List of countries and dependencies by population ...
,
Colombia Colombia, officially the Republic of Colombia, is a country primarily located in South America with Insular region of Colombia, insular regions in North America. The Colombian mainland is bordered by the Caribbean Sea to the north, Venezuel ...
,
Ecuador Ecuador, officially the Republic of Ecuador, is a country in northwestern South America, bordered by Colombia on the north, Peru on the east and south, and the Pacific Ocean on the west. It also includes the Galápagos Province which contain ...
,
Peru Peru, officially the Republic of Peru, is a country in western South America. It is bordered in the north by Ecuador and Colombia, in the east by Brazil, in the southeast by Bolivia, in the south by Chile, and in the south and west by the Pac ...
, and
Bolivia Bolivia, officially the Plurinational State of Bolivia, is a landlocked country located in central South America. The country features diverse geography, including vast Amazonian plains, tropical lowlands, mountains, the Gran Chaco Province, w ...
. The western pygmy marmoset, ''C. pygmaea'', occurs in the state of Amazonas, Brazil, eastern Peru, southern Colombia, and north-eastern Ecuador. The eastern pygmy marmoset, ''C. niveiventris'', is also found in Amazonas, but also in
Acre The acre ( ) is a Unit of measurement, unit of land area used in the Imperial units, British imperial and the United States customary units#Area, United States customary systems. It is traditionally defined as the area of one Chain (unit), ch ...
, Brazil, eastern Peru, and northern Bolivia. The distribution of both species is often limited by rivers. They typically live in the understory of the mature evergreen forests and often near rivers.
Population density Population density (in agriculture: Standing stock (disambiguation), standing stock or plant density) is a measurement of population per unit land area. It is mostly applied to humans, but sometimes to other living organisms too. It is a key geog ...
is correlated with food-tree availability. They can be found between ground level and about into the trees, but generally do not enter the top of the
canopy Canopy may refer to: Plants * Canopy (biology), aboveground portion of plant community or crop (including forests) * Canopy (grape), aboveground portion of grapes Religion and ceremonies * Baldachin or canopy of state, typically placed over an a ...
. They are often found in areas having standing water for more than three months of the year.


Diet

These monkeys have a specialized diet of tree gum. They gnaw holes in the bark of appropriate trees and vines with their specialized dentition to elicit the production of gum. When the sap puddles up in the hole, they lap it up with their tongues. They also lie in wait for
insect Insects (from Latin ') are Hexapoda, hexapod invertebrates of the class (biology), class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body (Insect morphology#Head, head, ...
s, especially
butterflies Butterflies are winged insects from the lepidopteran superfamily Papilionoidea, characterized by large, often brightly coloured wings that often fold together when at rest, and a conspicuous, fluttering flight. The oldest butterfly fossi ...
, which are attracted to the sap holes. They supplement their diet with nectar and fruit. A group's home range is , and feeding is usually concentrated on one or two trees at a time. When those become depleted, a group moves to a new home range.
Brown-mantled tamarin The brown-mantled tamarin (''Leontocebus fuscicollis''), also known as Spix's saddle-back tamarin, is a species of saddle-back tamarin. This New World monkey is found in the Southern American countries of Bolivia, Brazil and Peru. This Omnivore, ...
s are generally
sympatric In biology, two closely related species or populations are considered sympatric when they exist in the same geographic area and thus frequently encounter each other. An initially interbreeding population that splits into two or more distinct spe ...
with pygmy marmosets and often raid pygmy marmosets' gum holes. Pygmy marmosets have adapted insect-like claws, known as tegulae, to engage in a high degree of claw-clinging behaviors associated with plant
exudate An exudate is a fluid released by an organism through pores or a wound, a process known as exuding or exudation. ''Exudate'' is derived from ''exude'' 'to ooze' from Latin language, Latin 'to (ooze out) sweat' (' 'out' and ' 'to sweat'). Medi ...
exploitation. Claw-clinging is primarily used during feeding, but also during plant exudate foraging.


Behaviour

A pygmy marmoset group, ranging from two to nine members, contains one or two adult males and one or two adult females, including a single breeding female and her offspring. Interbirth interval ranges from 149–746 days. In contrast to other callitrichines, no relationship exists between the number of adult males and the number of infants and offspring. A significant positive relationship exists, though, between the number of juveniles and the number of adult and subadult group members. Young marmosets typically remain in the group for two consecutive birth cycles. The pygmy marmoset uses special types of communication to give alerts and warning to its family members. These include chemical, vocal, and visual types of communication. It is believed to serve to promote group cohesion and avoidance of other family groups.


Social systems

Infant pygmy marmosets, along with their parents, twins, and other siblings, form co-operative care groups.
Babbling A babbling infant, age 6 months, making ''ba'' and ''ma'' sounds Babbling is a stage in child development and a state in language acquisition during which an infant appears to be experimenting with uttering articulate sounds, but does not y ...
, or vocalizing, by the infant marmoset is a key part of its relationships with its family members and is a major part of its development. As the infant develops, the babbling gradually changes to resemble and eventually become adult vocalization. Many similarities are seen between the development of vocalization in infant pygmy marmosets and speech in infant humans. Vocalizing gives the infant advantages, such as increased care, and allows the entire family to coordinate their activities without seeing each other. Siblings also participate in infant care. Infant marmosets require the most attention, so having more family members participating in the care decreases the cost for any individual and also teaches parenting skills to the juvenile marmosets. Members of the group, usually female, may even put off their own reproduction through a temporary cessation of ovulation to care for the offspring of others in the group. The ideal number of caregivers for an infant marmoset has been shown to be around five individuals. Caregivers are responsible for finding food for the infants and helping the father watch for
predators Predation is a biological interaction in which one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not kill ...
. Pygmy marmosets are not seasonal breeders and usually give birth to twins once or twice a year. Single births, however, occur in 16% and triplet births occur in 8% of pregnancies. The pygmy marmoset is usually
monogamous Monogamy ( ) is a relationship of two individuals in which they form a mutual and exclusive intimate partnership. Having only one partner at any one time, whether for life or serial monogamy, contrasts with various forms of non-monogamy (e.g. ...
, though some variation happens within the species in terms of breeding systems.
Polyandry Polyandry (; ) is a form of polygamy in which a woman takes two or more husbands at the same time. Polyandry is contrasted with polygyny, involving one male and two or more females. If a marriage involves a plural number of "husbands and wives ...
also occurs, as male marmosets are responsible for carrying the infants on their backs. Having a second male to carry the offspring can be beneficial, as marmoset litters are often twins and this decreases the physiological cost to any particular male. The daily range of pygmy marmosets, however, is relatively small, which decreases the rate of polyandry. Male and female pygmy marmosets show differences in foraging and feeding behavior, although male and female dominance and aggressive behavior vary within the species. Males have less time to search out food sources and forage due to the constraints of their infant-caring responsibilities and predator vigilance. Without an infant to carry, female pygmy marmosets have greater freedom to forage, giving them an apparent feeding priority, which may serve to compensate mothers for the energetic costs of carrying and lactating for two offspring at a time. Since breeding priority is also given to females without offspring, the argument is weakened. Instead, female feeding priority may have evolved through
sexual selection Sexual selection is a mechanism of evolution in which members of one sex mate choice, choose mates of the other sex to mating, mate with (intersexual selection), and compete with members of the same sex for access to members of the opposite sex ...
. Females may choose mates that invest more time in infant care and predator vigilance. Such males have less time to look for food, allowing the female feeding priority.


Communication

Pygmy marmosets are well known for their communication abilities, including an intricate system of calls. The trill is used during feeding, foraging, and when travelling and the group is close together. The J-call is a series of fast notes repeated by the caller and is used at medium distances. Both calls are used as
contact calls Contact calls are seemingly haphazard sounds made by many social animals (such as a chicken's cluck). Contact calls are unlike other calls (such as alarm calls) in that they are not usually widely used, conspicuous calls, but rather short exclamatio ...
. The long call is used when the group is spread out over distances greater than 10 m or in response to a neighboring group. The pygmy marmoset uses the trill for short-distance communication, J-calls for intermediate distances, and long calls for long distances; these have respectively decreasing frequencies. They interpret these calls not only by type, but also through subtle sonic variance, by individual calling. Research based on audio playback tests shows that calls recorded from different individuals in captivity varied significantly in all seven auditory parameters analyzed for each type of call. Behavioral responses to trills were greatest when the caller was the dominant male of the group. Responses to J-calls were greatest when the caller was the monkey's mate or a same-sex monkey from outside the group. Varying responses to individual callers were only observed when the call was given spontaneously from another animal rather than being played back from a recording, with one exception. That exception was that male monkeys responded to playbacks of their own calls differently from those of other monkeys, when the call was played back from a familiar location. The pygmy marmoset is thought to react at first to the type of call that is being made and then adjusts its behavior slightly to react to the specific individual that is making the call. This allows the marmoset to react appropriately to all calls, but show some variation when the call gives extra information. Environmental factors play a role in communication by affecting the
frequency Frequency is the number of occurrences of a repeating event per unit of time. Frequency is an important parameter used in science and engineering to specify the rate of oscillatory and vibratory phenomena, such as mechanical vibrations, audio ...
of the signal and how far the signal can travel and still be audible to communicate the desired message. Since pygmy marmosets are often found in the rain forest, plant life and the humid atmosphere add to the normal absorption and scattering of sound. Because low-frequency calls are affected less by the disturbances than high-frequency ones, they are used for communication across longer distances. The pygmy marmoset changes the characteristics of its calls when its social environment is changed. Adult marmosets show modifications in the structure of their calls, which mimic those of their group members. In addition to changes of existing calls, novel calls may be heard from marmosets after pairing. Pygmy marmosets have other ways to communicate information about matters such as a female's ovulatory state. New World monkeys do not show genital swelling during
ovulation Ovulation is an important part of the menstrual cycle in female vertebrates where the egg cells are released from the ovaries as part of the ovarian cycle. In female humans ovulation typically occurs near the midpoint in the menstrual cycle and ...
as female Old World monkeys do. Instead, a lack of female aggression towards males can serve as a signal of ovulation. Scent glands on her chest, anus, and genitals are also rubbed on surfaces, which leave chemical signals about the reproductive state of the female. Pygmy marmosets also perform visual displays such as strutting, back-arching, and
piloerection Goose bumps, goosebumps or goose pimples are the bumps on a person's skin at the base of body hairs which may involuntarily develop when a person is tickled, cold or experiencing strong emotions such as fear, euphoria or sexual arousal. The f ...
when they feel threatened or to show dominance.


Conservation

Both species of pygmy marmosets are listed as vulnerable on the
IUCN Red List The International Union for Conservation of Nature (IUCN) Red List of Threatened Species, also known as the IUCN Red List or Red Data Book, founded in 1964, is an inventory of the global conservation status and extinction risk of biological ...
of Threatened Species. They are threatened by habitat loss in some areas of their range, and by the
pet trade Wildlife trade refers to the exchange of products derived from non-domesticated animals or plants usually extracted from their natural environment or raised under controlled conditions. It can involve the trade of living or dead individuals, tis ...
in others (i.e. Ecuador). Interaction between humans and pygmy marmosets is associated with a number of behavioral changes in the animal, including social
play Play most commonly refers to: * Play (activity), an activity done for enjoyment * Play (theatre), a work of drama Play may refer also to: Computers and technology * Google Play, a digital content service * Play Framework, a Java framework * P ...
and vocalization, both of which are important to communication between animals in the species. Particularly in areas of heavy tourism, pygmy marmosets have a tendency to be less noisy, less aggressive, and less playful with other individuals. They are also pushed into higher strata of the rainforest than they would normally prefer. Tourism in areas native to the pygmy marmoset is also correlated with increased capture of the animal. Due to its small size and relatively docile nature, captured pygmy marmosets are often found in exotic pet trades. Capture causes even more behavioral variations, including a decrease in both the number and the sound level of vocalizations. Pygmy marmosets can also be found at local zoos, where they exist in groups.


As pets

Known in the pet trade as finger monkeys, their value is associated with their being the smallest primate in the world. Listed as Vulnerable to extinction, they are rare to find in the market for purchase. Prices range from $1,000 to $4,000. Generally, a pygmy marmoset's lifespan is 15 to 20 years; they are known to have a shorter life in the wild mainly because they fall out of trees. Another expense for these creatures as pets is the necessary essentials to maintain them. Creating an environment similar to where they are from is important. For food, these creatures as pets are often fed fruits, insects, and smaller lizards. As pets, a baby pygmy marmoset needs to be fed every two hours for at least two weeks. Understanding their natural diet is also important because it helps maintain their good health from the necessary protein, calcium, and other nutrients they need to survive. In the United States, each state has different regulations regarding ownership of
pet monkey A pet monkey is a monkey kept as a pet. Monkeys are beloved for their entertainment value, resemblance to humans, and human-like abilities, but the practice of keeping monkeys as pets is criticized by primatologists and zoologists due to issues ...
s. Another factor that needs to be considered is that a regular veterinarian might not be able to help provide medical evaluations or care; one would need to seek out a veterinarian with a primate specialization. In South America, either importing or exporting these creatures is illegal. Understanding the laws within those countries is important when considering owning or taking care of a pygmy marmoset. Many people do not agree that pygmy marmosets should be pets. The argument is usually that they have a longer lifespan when they are in good care from a human. However, the UK RSPCA says they should "not be considered as pets in the accepted sense of the word. They are wild, undomesticated animals that cannot be house trained or fully tamed".


In popular culture

* Fingerlings, the hit toy of Christmas 2017 produced by
WowWee WowWee Group Limited is a privately held, Hong Kong–based Canadian consumer technology company. History Initially from Canada, the two founding brothers (Richard and Peter Yanofsky) moved to Hong Kong to form the company in 1982, as an indepe ...
, is based on pygmy marmosets.


See also

* *


References


External links


Twin albino pygmy marmosets born in Sweden

Primate Info Net ''Callithrix pygmaea'' Factsheet
{{Taxonbar, from=Q19826010 Mammals of Bolivia Primates of Brazil Mammals of Colombia Mammals of Ecuador Mammals of Peru Taxa named by John Edward Gray