Although relatively small, mongooses are considered one of the most invasive species today. Native to most of Africa and parts of southern Asia, mongooses range in size from 7 inches to 2 feet long [2]. These mammals possess brown or gray fur that covers their long, slender bodies and short legs.

Mongooses are carnivorous mammals that feed on rodents, birds, reptiles, frogs, insects, and worms, with the occasional supplement of fruit in their diet [2]. Mongooses are famous for intrepidly attacking snakes because they are very quick during conflicts and can easily dodge the snake.

While mongooses seem beneficial to protect land from invading snakes, they prove to be increasingly injurious in their nonnative lands. During the 1800s, mongooses were introduced species to several islands in Hawaii and Puerto Rico [3]. They were originally brought to these areas to protect sugar cane fields from rat and snake destruction and crowd control. Instead of regulating the population and damage, mongooses actually harm more species in the wildlife than desired.  So far, mongooses have triggered the extinction of 12 reptile and amphibian species from Puerto Rico, the West Indies, and Jamaica [1]. These mongooses threaten the survival of many native species like birds and reptiles. Other species are now susceptible to extinction because mongooses are now fully settled in the islands of Hawaii. Because of their ravenous appetite and break-neck reflex, mongooses are considered one of the most invasive species.

The African elephant is the largest land animal on the Earth. They differ from the Asian elephant in that they are slightly larger in build and have larger ears. Their large ears are used to radiate excess heat [5]. The African elephant possesses a trunk that is used to smell, breath, bathe, trumpet, drink, and grab things for their meal. Its trunk contains about 100,000 different muscles [4]. They have tusks that are used to dig for food and water and to strip bark from trees.

Elephants are herbivores that eat roots, grasses, fruit and bark. These gentle creatures are found in the tropical rainforest zone of west and central Africa or in the eastern and southern Africa with the highest densities [5]. This species lives up to 70 years. The pregnancy of a female elephant is an extensive 22 months [5].

The African elephant is listed as Endangered under the U.S. Endangered Species Act and by the International Union for the Conservation of Nature and Natural Services [6]. African elephants are threatened by poaching and habitat loss. Many elephants have been killed for their ivory tusks. Their tusks are used for piano keys, jewelry, etc while their meat is used by the local people and are highly prized among game hunters [6]. For many years, countries have suffered serious declines in elephant populations. From 1979 to 1989, the species population was estimated to have dropped from 1.2 million to 600,000 [6]. While a ban has been implemented to protect the elephants, the species remains threatened by illegal hunting for meet and ivory, habitat loss, and human-elephant conflict. If we do not fervently protect and preserve elephants and their habitats, elephants may become locally extinct in some parts of Africa within 50 years [6]. These endangered species are also foundation species. Without them, many other species will collapse. 

Busy, flat-tailed, and productive, beavers are pivotal keystone species that are crucial to life’s biodiversity. Among the largest of rodents, beavers are herbivores usually eating leaves, bark, twig, roots, and aquatic plants [7]. Known for building dams, beavers quickly burrow in the banks of rivers and lakes. By felling and gnawing at trees with their strong teeth and jaws, they create massive log, branch, and mud structures to block streams and turn forests into large ponds [7]. These dammed streams in shallow valleys become productive wetlands, where it provides a rich, watery habitat for numerous species. Almost half of all endangered and threatened species rely on wetlands, one of the world’s most valuable land-based ecosystems, for survival [9].

Beavers can live up to 24 years and can weigh up to 60 pounds. They are graceful in the water while they waddle on the land. These use their webbed feet as swimming fins and their paddle-shaped tails as rudders, which allows them to be excellent swimmers [7]. They also have naturally oily and waterproof fur. Beavers life in domelike homes called lodges that are made up of branches and mud [7]. They locate their lodges in the middle of the ponds and can only be reached by underwater entrances [7].

Beavers are considered important keystone species because they provide many benefits that other species, including humans, reap. Humans receive direct benefits from beaver ponds including a decrease in damaging floods, recharge drinking water aquifers, remove pollutants, drought protection, and decrease erosion [8]. Other benefits of beaver ponds include that they produce food for fish and other animals, support biodiversity, including 43% of our endangered species, create vital habitats, preserve open space, and maintains river flow [8]. Beaver ponds also provide greater opportunities for wildlife observation, fishing, bird watching, etc. Through all of these benefits, beavers should be considered as a favorite keystone species. 

Often mistaken as a jellyfish, the Portuguese man-of-war is a siphonophore, constructed of a colony of organisms working together. This carnivorous invertebrate is comprised of four separate polyps. The uppermost polyp is a gas-filled, purple-blue colored bladder called a pneumatophore that floats atop of the water [10]. The long, thin tentacles make up the second organism of the man-of-war. These tendrils can extend up to 50 meters in length below the surface. They are covered in venom-filled namatocysts used to paralyze and kill fish and other small creatures [10]. The muscles in the tentacles draw up the prey to the polyp containing the digestive organisms while the fourth and final polyp contains the reproductive organisms [10].

These menacing organisms are found in warm waters throughout the world’s oceans. Their transparent blue and purple coloration camouflages them against the ocean waves which makes it easy for humans to be enveloped in their tentacles. While hunting, their tentacles extend to full length to act as a floating net [11]. They utilize the drift of the currents or the wind to move. To avoid threats on the surface, they are able to deflate their air bags and briefly submerge under water [10].

Even though they are relatively dependent on other factors to move, their adaptations are perilous enough to their prey for the Portuguese man-of-war to be considered as the coolest predator adaptation. They adapt with their environment to survive. 

There are more than 120 species of puffer fish worldwide. Puffer fish can grow up to 3 feet long and are found in tropical and subtropical ocean waters, but some live in brackish, fresh water [13]. This diversified fish has a diet that feeds mostly on algae and invertebrates.

Because of their inability to swim quickly and vulnerability to predators, puffer fish have developed an adaptation that will make them virtually inedible. The puffer fish use their highly elastic stomachs to ingest huge amounts of water to turn themselves into a ball several times their size with spines on their skin to make them even less palatable [12].  The tough, leathery body of a puffer fish will protect it from predators that can neither grip its body nor bite through its skin [13]. Puffer fish also contain tetrodotoxin, a toxic substance that makes them foul tasting and often lethal to fish predators. There is enough toxin in one puffer fish to kill 30 adult humans [12]. But that’s not all. The puffer fish also exhibit wild markings and colors to advertise their toxicity, which scares off predators, or they will camouflage with their environment with muted colors [13].

Through all of these adaptations, it is evident that the puffer fish is resilient and possesses the coolest prey adaptation.