Black Spider Monkey - Endangered

Melany Murillo

Common and scientific name, organism range

Ateles paniscus- scientific name

Black spider monkey- common name

Organism range- Their range extends north into French Guiana, Surinam, and eastern Guyana but they are restricted to the forests east of the Guianan Highlands in these countries (Collins & Dubach 2000; Groves 2001). If they are present in Venezuela, it is at the very eastern tip of the country.

size, sexual dimorphism


    16-24 inches


    15-19 pounds


    16-24 inches (body), 24-32 inches (tail)

  • In general, spider monkeys are not characterized by a high degree of sexual dimorphism; the average weight for wild black spider monkey males is 10.8 kg (23.8 lb) while females weigh 9.66 kg (21.3 lb) on average (Youlatos 1994; Di Fiore & Campbell 2007). The height of male spider monkey averages 557 mm (1.83 ft) while females average 552 mm (1.81 ft) (Youlatos 1994).

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How does it interact with other organisms in its ecosystem(specific niche), Include a food web.

As large-bodied frugivores, black spider monkeys are important seed dispersers within the rainforest ecosystem and play a crucial role in regenerating tropical forests.

Why is it endangered and how did it become this way?

The destruction of tropical rainforests and threats from hunting pose the greatest challenge to the black spider monkey’s survival. Because they prefer mature tropical forests and seldom venture into disturbed habitats, these monkeys are especially vulnerable to the effects of forest fragmentation

How did the carrying capacity of its environment change? How many are there compared to previous numbers? Habitat Fragmentation? Pollution?

  • Carrying Capacity (K)- While the average troop size of the spider monkey is about 20-30 spider monkeys, the capacity for any troop size is estimated to be 70 individuals, however not every black-headed spider monkey troop would be able to reach this capacity due to the limited resources in the biome.
  • Due to their status as critically endangered, there are no accurate population sizes of black-headed spider monkeys, but the population of spider monkeys as a whole is estimated at 2,000 compared to 2800 2 decades ago.
  • logging, hunting, and forest fragment size
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Based on the fact that a female spider monkey produces a single offspring every 3-4 years and based on the amount of deaths of the spider monkey population per year, there could be a growth of 400 spider monkeys every 3-4 years if the population was given unlimited resources.
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Spider Monkey populations have a small population and experience a steady decrease in growth in time as the population approaches its carrying capacity, therefore it has a logistic growth rate of about 400 per 3-4 years but begins to level-off as it approaches 6000.
  • Limiting Resources- Limiting resources of the black-headed spider monkey are the resources found in the tropical rainforest. The amount of available fruit, which the spider monkeys consume, affects the ability of the population to grow. In addition, the size of their habitat is also a limiting resource, because the less area the spider monkeys have, the fewer of them are able to find shelter and hide from predators and hunters.
  • Keystone Species- Yes, Spider Monkeys are incredibly important to the survival of the tropical rainforest. The fruits and nuts that the monkeys ingest also hold seeds that are expelled from the monkey with the rest of its waste. These seeds, already in a natural fertilizer, are able to take root in the ground and begin to sprout beginning the growth of a new organism. Without spider monkeys, these trees and plants would be unable to produce new offspring and they would become extinct, which is why they are so vital to the biome.
  • it would take a long time for it to recover and the possibility exists that if reduced to small enough numbers, the population could not rebound (McFarland Symington 1988; Rylands & Keuroghlian 1988).
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My call to action

I will spread awareness at my school about the importance of the Black Spider Monkey and what we can do to help their situation.