Vestigial organs are adaptations that have become useless. In humans, vestigial organs include the appendix, thought to be left over from when the human diet was primarily vegetation; the coccyx, a vestigial tail; and gill slits that are found in human embryos, though embryos never breathe through them.
An adaptation is a mutation, or genetic change, that helps an organism, such as a plant or animal, survive in its environment. Due to the helpful nature of the mutation, it is passed down from one generation to the next. As more and more organisms inherit the mutation, the mutation becomes a typical part of the species. The mutation has become an adaptation.
Structural and Behavioral Adaptations
An adaptation can be structural, meaning it is a physical part of the organism. An adaptation can also be behavioral, affecting the way an organism acts.
An example of a structural adaptation is the way some plants have adapted to life in the desert. Deserts are dry, hot places. Plants called succulents have adapted to this climate by storing water in their thick stems and leaves.
Animal migration is an example of a behavioral adaptation. Grey whales migrate thousands of miles every year as they swim from the cold Arctic Ocean to the warm waters off the coast of Mexico. Grey whale calves are born in the warm water, and then travel in groups called pods to the nutrient-rich waters of the Arctic.
Some adaptations are called exaptations. An exaptation is an adaptation developed for one purpose, but used for another. Feathers were probably adaptations for keeping the animal warm that were later used for flight, making feathers an exaptation for flying.
Some adaptations, on the other hand, become useless. These adaptations are vestigial: remaining but functionless. Whales and dolphins have vestigial leg bones, the remains of an adaptation (legs) that their ancestors used to walk.
Adaptations usually develop in response to a change in the organisms habitat.
A famous example of an animal adapting to a change in its environment is the English peppered moth. Prior to the 19th century, the most common type of this moth was cream-colored with darker spots. Few peppered moths displayed a mutation of being grey or black.
As the Industrial Revolution changed the environment, the appearance of the peppered moth changed. The darker-colored moths, which were rare, began to thrive in the urban atmosphere. Their sooty color blended in with the trees stained by industrial pollution. Birds couldnt see the dark moths, so they ate the cream-colored moths instead. The cream-colored moths began to make a comeback after the United Kingdom passed laws that limited air pollution.
Sometimes, an organism develops an adaptation or set of adaptations that create an entirely new species. This process is known as speciation.
The physical isolation or specialization of a species can lead to speciation.
The wide variety of marsupials in Oceania is an example of how organisms adapt to an isolated habitat. Marsupials, mammals that carry their young in pouches, arrived in Oceania before the land split with Asia. Placental mammals, animals that carry their young in the mothers womb, came to dominate every other continent, but not Oceania. There, marsupials faced no competition.
Koalas, for instance, adapted to feed on eucalyptus trees, which are native to Australia. The extinct Tasmanian tiger was a carnivorous marsupial and adapted to the niche filled by big cats like tigers on other continents. Marsupials in Oceania are an example of adaptive radiation, a type of speciation in which species develop to fill a variety of empty ecological niches.
The cichlid fish found in Africas Lake Malawi exhibit another type of speciation, sympatric speciation. Sympatric speciation is the opposite of physical isolation. It happens when species share the same habitat. Adaptations have allowed hundreds of varieties of cichlids to live in Lake Malawi. Each species of cichlid has a unique, specialized diet: One type of cichlid may eat only insects, another may eat only algae, another may feed only on other fish.
Organisms sometimes adapt to and with other organisms. This is called coadaptation. Certain flowers have adapted their pollen to appeal to the hummingbirds nutritional needs. Hummingbirds have adapted long, thin beaks to extract the pollen from certain flowers. In this relationship, the hummingbird gets food, while the plants pollen is distributed. The coadaptation is beneficial to both organisms.
Mimicry is another type of coadaptation. With mimicry, one organism has adapted to resemble another. The harmless king snake (sometimes called a milk snake) has adapted a color pattern that resembles the deadly coral snake. This mimicry keeps predators away from the king snake.
The mimic octopus has behavioral as well as structural adaptations. This species of octopus can mimic the look and movements of animals such as sea stars, crabs, jellyfish, and shrimp.
Coadaptation can also limit an organisms ability to adapt to new changes in their habitat. This can lead to co-extinction. In Southern England, the large blue butterfly adapted to eat red ants. When human development reduced the red ants habitat, the local extinction of the red ant led to the local extinction of the large blue butterfly.
Term Part of Speech Definition Encyclopedic Entry adapt Verb
to adjust to new surroundings or a new situation.
a modification of an organism or its parts that makes it more fit for existence. An adaptation is passed from generation to generation.
Encyclopedic Entry: adaptation adaptive radiation Noun
process in which many species develop from the same ancestral species to fill a variety of different roles in the environment.
air pollution Noun
harmful chemicals in the atmosphere.
Encyclopedic Entry: air pollution algae Plural Noun
(singular: alga) diverse group of aquatic organisms, the largest of which are seaweeds.
region at Earth's extreme north, encompassed by the Arctic Circle.
Encyclopedic Entry: Arctic behavioral adaptation Noun
way an organism acts that is passed down to the next generation.
big cat Noun
large predators, including tigers, lions, jaguars, and leopards.
spiny-finned freshwater fish.
all weather conditions for a given location over a period of time.
Encyclopedic Entry: climate coadaptation Noun
the process in which organisms develop in close relationship to one another.
edge of land along the sea or other large body of water.
Encyclopedic Entry: coast co-extinction Noun
the process in which the loss of one species leads to the loss of another species.
one of the seven main land masses on Earth.
Encyclopedic Entry: continent desert Noun
area of land that receives no more than 25 centimeters (10 inches) of precipitation a year.
Encyclopedic Entry: desert development Noun
growth, or changing from one condition to another.
Encyclopedic Entry: development diet Noun
foods eaten by a specific group of people or other organisms.
Encyclopedic Entry: diet distribute Verb
to divide and spread out materials.
to overpower or control.
conditions that surround and influence an organism or community.
tree native to Oceania.
adaptation that developed for one purpose but is used for another.
no longer existing.
to pull out.
group in a species made up of members that are roughly the same age.
having to do with genes, inherited characteristics or heredity.
environment where an organism lives throughout the year or for shorter periods of time.
Encyclopedic Entry: habitat hummingbird Noun
type of very small bird.
having to do with factories or mechanical production.
Industrial Revolution Noun
change in economic and social activities, beginning in the 18th century, brought by the replacement of hand tools with machinery and mass production.
to receive from ancestors.
state of being alone or separated from a community.
animal with hair that gives birth to live offspring. Female mammals produce milk to feed their offspring.
mammal that carries its young in a pouch on the mother's body.
to move from one place or activity to another.
movement of a group of people or animals from one place to another.
to copy another organism's appearance or behavior.
sudden variation in one or more characteristics caused by a change in a gene or chromosome.
role and space of a species within an ecosystem.
substance an organism needs for energy, growth, and life.
Encyclopedic Entry: nutrient Oceania Noun
region including island groups in the South Pacific.
placental mammal Noun
animal (mammal) characterized by the fetus developing inside the body of the mother, in an organ called the placenta.
powdery material produced by plants.
introduction of harmful materials into the environment.
Encyclopedic Entry: pollution resemble Verb
to look like.
particles produced by burning a substance such as coal, wood, or oil.
process by which one or more populations of a species become genetically different enough to form a new species.
Encyclopedic Entry: speciation species Noun
group of similar organisms that can reproduce with each other.
structural adaptation Noun
way an organism physically develops that is passed down from one generation to the next.
type of plant that has thick leaves and stems for storing water.
sympatric speciation Noun
development of many similar species in a single habitat, each with a different specialization.
to develop and be successful.
one of a kind.
having to do with city life.
having to do with a body part, or remnant of a body part, that no longer serves any useful function.
organ in which an embryo and fetus develops. Also called the uterus.
offspring or children.