Category Plants & Animals

WHAT IS SYMBIOSIS?

When both partners benefit equally from a partnership, they are said to be in a symbiotic relationship. There are many such relationships in the natural world. For example, when a bee goes to a flower to collect nectar, it also brings about pollination by carrying pollen on its furry body from one flower to the next. Both the bee and the flower benefit.

A symbiosis is an evolved interaction or close living relationship between organisms from different species, usually with benefits to one or both of the individuals involved. Symbioses may be ‘obligate’, in which case the relationship between the two species is so interdependent, that each of the organisms is unable to survive without the other, or ‘facultative’, in which the two species engage in a symbiotic partnership through choice, and can survive individually. Obligate symbioses are often evolved over a long period of time, while facultative symbioses may be more modern, behavioral adaptions; given time, facultative symbioses may evolve into obligate symbioses.

Endosymbiosis is a symbiotic relationship, occurring when one of the symbiotic partners lives within the body of the other. Endosymbiosis can take place either within the cells (intercellular symbiosis) of the ‘host’ organism, or outside the cells (extracellular symbiosis). On the other hand, ectosymbiosis is a symbiotic relationship in which one organism lives on the body surface of the host, including the lining of the digestive tract, or exocrine glands such as mucus or sweat glands.

Mutualisms are a form of symbiosis in which both symbiotic partners benefit from the interaction, often resulting in a significant fitness gain for either one or both parties. Mutualisms can take the form of resource-resource relationships, service-resource relationships, or service-service relationships.

Resource-resource mutualisms (also known as ‘trophic mutualisms’) happen through the exchange of one resource for another between the two organisms involved. Resource-resource mutualisms most often occur between an autotroph (a photosynthesizing organism) and a heterotroph (an organism which must absorb or ingest food to gain energy). Most plants have a trophic mutualism called a mycorrhizal association, which is a symbiosis between the roots of the plants and a fungus. The fungus colonizes the plants roots and is provided with carbohydrates, sucrose and glucose. In exchange, the plant benefits from the fungi’s higher water and mineral absorption capabilities.

Service-resource mutualisms occur when the symbiotic partner provides a service in exchange for a resource reward. One of the best known examples of this is the exchange between plants and their pollinators. While visiting the plants to gain a supply of energy-rich nectar, the pollinator (insects, birds, moths, bats, etc.), provides the plant with the service benefit of being pollinated, while ensuring their own pollen is distributed when the pollinator visits more plants of the same species.

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HOW DO LIVING THINGS SURVIVE TOGETHER?

All living things are linked in complicated food. Webs, relying on each other for nourishment, but some animals and plants have very special relationships, where a partnership may benefit one partner or both.

Relationships are an important component of life. In such relationships, plants or animals of different species may be dependent on one another for survival. They may share habitats or lifestyles or interact in a specific way to benefit from the presence of another organism.

We often refer to animals living in tandem as ‘associates.” The relationship between associates and their hosts can be described as mutualistic, commensal, or parasitic. In a mutualistic relationship, both animals benefit from living together. Commensal organisms cause no harm to their hosts, but receive some benefit from living with them. Parasites actually feed off their host organism, thus causing harm to the host.

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HOW DO THE MAIN ECOSYSTEMS DIFFER?

Terrestrial ecosystems are many because there are so many different sorts of places on Earth. Some of the most common terrestrial ecosystems that are found are the following:

Rainforests – Rainforests usually have extremely dense ecosystems because there are so many different types of animals all living in a very small area.

Tundra – As mentioned above, tundra usually have relatively simple ecosystems because of the limited amount of life that can be supported in these harsh conditions.

Deserts – Quite the opposite of tundra in many ways, but still harsh, more animals live in the extreme heat than live in the extreme cold of Antarctica, for instance.

Savannas – These differ from deserts because of the amount of rain that they get each year. Whereas deserts get only a tiny amount of precipitation every tea, savannas tend to be a bit wetter which is better for supporting more life.

Forests – There are many different types of forests all over the world including deciduous forests and coniferous forests. These can support a lot of life and can have very complex ecosystems.

Grasslands – Grasslands support a wide variety of life and can have very complex and involved ecosystems.

Since there are so many different types of terrestrial ecosystems, it can be difficult to make generalizations that cover them all.

Because terrestrial ecosystems are so diverse, it is difficult to make generalizations about them. However, a few things are true almost all of the time. For instance, most contain herbivores that eat plants (that get their sustenance from the sun and the soil) and all have carnivores that eat herbivores and other carnivores. Some places, such the poles, contain mainly carnivores because not plant life grows. A lot of animals and plants that grow and live in terrestrial ecosystems also interact with freshwater and sometimes even ocean ecosystems.

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WHERE ARE THE MAIN ECOSYSTEMS OF THE WORLD?

The map below shows the main ways in which the Earth can be divided into different ecosystems. These are based mainly on the kind of plants that grow in an area, as all other living things rely directly or indirectly on plants for their food. Of course, there are many smaller ecosystems within these broad divisions.

An ecosystem consists of all the living and non-living things in a specific natural setting. Plants, animals, insects, microorganisms, rocks, soil, water and sunlight are major components of many ecosystems. All types of ecosystems fall into one of two categories: terrestrial or aquatic. Terrestrial ecosystems are land-based, while aquatic are water-based. The major types of ecosystems are forests, grasslands, deserts, tundra, freshwater and marine. The word “biome” may also be used to describe terrestrial ecosystems which extend across a large geographic area, such as tundra. Keep in mind, however, that within any ecosystem, specific features vary widely – for instance, an oceanic ecosystem in the Caribbean Sea will contain vastly different species than an oceanic ecosystem in the Gulf of Alaska.

Forest Ecosystems

Forest ecosystems are classified according to their climate type as tropical, temperate or boreal. In the tropics, rainforest ecosystems contain more diverse flora and fauna than ecosystems in any other region on earth. In these warm, moisture-laden environments, trees grow tall and foliage is lush and dense, with species inhabiting the forest floor all the way up to the canopy. In temperate zones, forest ecosystems may be deciduous, coniferous or oftentimes a mixture of both, in which some trees shed their leaves each fall, while others remain evergreen year-round. In the far north, just south of the Arctic, boreal forests – also known as taiga – feature abundant coniferous trees.

Grassland Ecosystems

Different types of grassland ecosystems can be found in prairies, savannas and steppes. Grassland ecosystems are typically found in tropical or temperate regions, although they can exist in colder areas as well, as is the case with the well-known Siberian steppe. Grasslands share the common climactic characteristic of semi-aridity. Trees are sparse or nonexistent, but flowers may be interspersed with the grasses. Grasslands provide an ideal environment for grazing animals.

Desert Ecosystems

The common defining feature among desert ecosystems is low precipitation, generally less than 25 centimeters, or 10 inches, per year. Not all deserts are hot – desert ecosystems can exist from the tropics to the arctic, but regardless of latitude, deserts are often windy. Some deserts contain sand dunes, while others feature mostly rock. Vegetation is sparse or nonexistent, and any animal species, such as insects, reptiles and birds, must be highly adapted to the dry conditions.

Tundra Ecosystems

As with deserts, a harsh environment characterizes ecosystems in the tundra. In the snow-covered, windswept, treeless tundra, the soil may be frozen year-round, a condition known as permafrost. During the brief spring and summer, snows melt, producing shallow ponds which attract migrating waterfowl. Lichens and small flowers may become visible during this time of year. The term “tundra” most commonly denotes polar areas, but at lower latitudes, tundra-like communities known as alpine tundra may be found at high elevations.

Freshwater Ecosystems

Freshwater ecosystems can be found in streams, rivers, springs, ponds, lakes, bogs and freshwater swamps. They are subdivided into two classes: those in which the water is nearly stationary, such as ponds, and those in which the water flows, such as creeks. Freshwater ecosystems are home to more than just fish: algae, plankton, insects, amphibians and underwater plants also inhabit them.

Marine Ecosystems

Marine ecosystems differ from freshwater ecosystems in that they contain saltwater, which usually supports different types of species than does freshwater. Marine ecosystems are the most abundant types of ecosystems in the word. They encompass not only the ocean floor and surface but also tidal zones, estuaries, salt marshes and saltwater swamps, mangroves and coral reefs.

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WHICH MAMMAL IS THE FASTEST?

          The cheetah (Acinonyx jubatus) can reach 105km/h (68mph) when sprinting over a short distance. For animals, fast speed often means survival. It means outrunning predators or catching prey. In order to be fast, every physiological characteristic is important. The ratio of height and weight, flexibility, and respiratory functioning are all things that affect speed. This article identifies the fastest mammals in the world and what makes them so fast.

          The cheetah is the fastest mammal on earth and can reach speeds of 68 to 75 miles per hour (mph). Though not the best for endurance, they run in short burst of 60 seconds or so. This feline is built for speed. They have large nasal passages that lead to large lungs, even the heart is enlarged to allow for maximum oxygen in the blood. Cheetahs use their tail for balance and spend more time with their paws in the air than on the ground while running.

          The second fastest mammal on earth never runs on the ground. The Free-tailed bat soars through the nighttime air at 60 mph and it is their “free” or unattached tail that allows them to reach such speeds. They inhabit every continent except Antarctica.

          After the Free-tailed bat is the Pronghorn, a graceful antelope that reaches speeds of up to 55 mph. While this antelope cannot outrun a cheetah in a head to head race, it can run for longer periods of time. That makes this mammal the fastest over long distances and the fastest in the Western Hemisphere. They are native to North America and live in wide, open grasslands. Scientists believe the Pronghorn evolved such high speeds to outrun predators. They share some of the same physical features as the cheetah: enlarged nasal passages, lungs, and heart.

          Sharing the number 3 spot on the list of the fastest mammals is the Springbok, an African antelope. This animal reaches the same speeds as the Pronghorn, 55 mph, though it cannot sustain over long distances.

          Number 4 on the list is the Wildebeest, another species of antelope. These mammals run up to speeds of 50 mph which allows them to escape lions, hyenas, cheetahs and leopards. Although more than their speed, it is their herding behavior that helps protect them from predators. Every year, wildebeests make a long migration following the pattern of rainy and dry seasons.

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DO ALL MAMMALS GIVE BIRTH TO LIVE YOUNG?

          Most mammal babies develop inside their mothers until they are ready to be born. The exceptions are the monotremes, a small group of mammals found in Australia. Like most reptiles, they lay eggs rather than giving birth to live young. Perhaps the best known of these is the duck-billed platypus.

          Of course, the platypus isn’t really a mixture of these other creatures. It just looks like it! The platypus is a semi-aquatic mammal native to Australia (including Tasmania) and Papua New Guinea.

          Along with four species of echidna (a mammal that looks a bit like a porcupine), the platypus is one of only five species of monotremes in the world. Monotremes are mammals that lay eggs instead of giving birth to live young.

          The platypus has a bill like a duck, a tail like a beaver, the skin and feet of an otter, and venom like a snake. These features truly make the platypus one of the most unique creatures on Earth. In fact, when the platypus was first discovered hundreds of years ago, scientists at the time thought it was an elaborate hoax.

          The name “platypus” comes from the Greek word for “flat-footed.” The male platypus has special spurs on its hind feet that it can use to defend itself by injecting painful venom into a predator. Although the venom isn’t deadly to humans, it can cause severe pain.

          The platypus can walk and run on land, but it moves awkwardly. Its webbed feet and waterproof skin help it to live much of the time in the water, where it feeds on insects, shellfish, worms, and other small creatures at the bottom of bodies of water.

          The platypus is mostly nocturnal and can spend up to 10 hours at a time in the water, searching for food. When it’s done swimming, the platypus likes to live in a burrow dug into the bank of a nearby body of water.

          The female platypus lays one or two eggs each season. When a baby platypus emerges from its shell, it’s about the size of a lima bean. Its mother will take care of it for three months or so until it’s ready to head out into the world on its own.

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