what is a keystone species?

what is a keystone species?

When studying the life sciences, there are a lot of in-depth concepts to take in. Depending on the the type of science you are studying, biology vs. evolution, for example, you may even have to learn a handful of mathematical formulas to fully appreciate the material. Here, we are just having a light-hearted overview of the life sciences, so a light serving of sativa will do just fine.

In my experience, sativa helps me to not get lost in wordy texts (reading that is not broken up by graphics/tables or formulas) and keep my mind sharp and able to take in all relevant information. Grinding about 60mg (less than 1/4 of a 1g bud) of sativa and smoking just a small pinch of that for over a 3-5hr period is perfect for maintaining a healthy attention span for learning.

Black Flower Science Co. does not claim to be a medical professional and does not offer recommendations as a substitute for medical advice. All advice and recommendations are based on personal experience of the benefits of medical marijuana. If you are experiencing severe or declining mental health symptoms, please seek the advice of a medical professional.

Ecology. The study of organisms’ interaction with each other and their environment.

These organisms can influence each other in an endless amount of ways, either directly or indirectly. They can operate in mutually beneficial relationships, share (or not share) resources, alter their environment with such behaviors as feeding or mass migration, or even sustain an entire ecosystem simply by functioning in their appropriate niche.

A species’ niche is a set of physical and biological conditions it requires to survive, grow and reproduce. There are two subsets of this: the fundamental and the realized niche. The fundamental niche is defined by the organism’s physiological capabilities, whereas the realized niche is defined by its interactions with other species.

​A predatory species fully functioning in its realized niche has the power to directly influence the relative abundance of sympatric species (species that share the same space/habitat).

This particular species does not even have to occur in larger numbers than its prey or rival predators. In this context, if the animal has a strong effect on its ecosystem disproportionate to its abundance, it is known as a keystone species. 

Pisaster ochraceous | USGS

Popular examples of keystone species are the sea otter and sea star, aka “starfish.”

Enhydra lutris, the sea otter is a carnivorous, aquatic mammal that takes residence off the Western coast from California to Alaska. It can weigh up to 100lbs, and can reach between 4-5 feet in length from head to tail. It feeds on clams, sea urchins, abalone and crabs, but the most important component of this diet is the sea urchin.

In 1971, zoologist James A. Estes and ecologist Robert T. Paine made a ground-breaking discovery regarding the interactions of species in the “marine analogue to the terrestrial rainforest”, the kelp forest. They knew that purple sea urchins grazed on the kelp, but the magnitude of that behavior’s effect because clearer when sea otters were absent from this habitat.

It was found that, if left unchecked, sea urchins were capable of clearing entire beds of kelp, not only exploiting their own resource, but ridding neighboring species of this life-giving algal species.

By regulating the urchins via predation, the sea otters prevented overgrazing and so ensured that the kelp persisted. Other marine herbivores and fish kept their natural habitat, and the ecosystem stayed intact.

In 1966, that same ecologist, Robert T. Paine experimented with the oceanside ecosystems of Washington’s Mukkaw Bay. The community of these shores consisted of a variety of marine invertebrates including snails, barnacles, mussels and starfish.

Paine observed that in the absence of another keystone species, the starfish species, Pisaster ochraceous, its prey species, a large, dark mussel, grew in abundance. This mussel ultimately drove all its neighboring species out of the prime real estate, eventually overtaking the habitat and available resources.

In the presence of P. ochraceous, though, the mussel would be healthily regulated, and this would prevent them from exploiting their own resources and exceeding their habitat’s carrying capacity. In addition, other species would persist alongside the mussel and starfish, and again, this ecosystem would remain intact.

It’s kind of crazy to think that just one species, one part of an entire ecosystem can play such a vital role in keeping it alive and functioning. The species doesn’t have to exercise some tremendous level of power or be particularly numerous. It just has to know its job and do it well.


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