Humans have identified about a quarter of a million different species of organisms
living in our oceans, but as the deep blue sea is largely unexplored
scientists suspect there are millions more still waiting to be discovered. It is estimated
that as much as 80% of all living creatures make their home in the ocean.
Each marine organism is specially adapted to live in the salty seawater of its ocean home.
Scientists use a variety of systems to classify ocean life. One of these systems classifies life
into five groups or kingdoms; animals, plants, protists, fungi, and bacteria. Let's explore
some of the intriguing life under the ocean surface starting with the largest; the blue whale
and working our way down to the smallest organisms so small they are each made of only one
cell. The first kingdom is animals. The members of this group can be both vertebrates (animals
with backbones) or invertebrates (animals without backbones). The enormous and stunning blue whale
is a vertebrate and it's not only the largest animal on earth, it is the largest animal to
have ever lived on earth. Its tongue alone can weigh as much as an elephant and this massive
marine creature can reach weights of 200 tons and grow to around 30 meters or 100 feet in length.
Blue whales live alone or in pairs in all the oceans, except the arctic.
In summer they feed on tiny krill in cool waters close to the North and South poles.
In winter, blue whales are found in warm, tropical waters near the earth's equator.
While whales must live in deep water, the members of our next kingdom, plants, are usually found in
shallow water. All marine plants need sunlight to survive. As a result most marine plants live near
the ocean's surface where they can capture energy from the sun. Ocean plants have special adaptions
that allow them to withstand salty waters and survive rough waves and strong currents but
like the plants that live on land marine plants also have roots, leaves, flowers, and seeds.
More than 50 species of seagrasses grow in beds or large patches on shallow seafloors.
Sometimes they cover vast areas and are known as seagrass meadows,
some so large they can be seen from space. The names of these plants,
turtle grass, surf grass, paddle grass, star grass, and more tell a story about their place
within ocean habitats. Seaweeds are different from seagrasses. They are actually not plants at all.
Seaweeds are algae and algae are a large part of our next kingdom of marine life
called protists. Many people consider algae with its slimy texture to be an annoyance
but algae plays an extremely important role in the ocean. Whether green, red,
or brown algae is the main food source that almost all marine life depends upon. Algae can be small,
such as the minuscule single-celled phytoplankton that drift in the seawater, or large, like the
giant kelp that can form massive underwater kelp forests. Many marine creatures make their homes in
these immense kelp forests which provide not only food, but also protection and camouflage. From the
giant kelp, we must zoom in to see the small organisms belonging to the next kingdom called
fungi. The vast majority of fungi on the entire earth is found on the land like mushrooms,
toadstools, mildews, molds, and yeasts, but a small number of species are found in the oceans.
Marine fungi can live in various places within the ocean. Some drift in the water, others find
homes on the sea floor, and some fungi attach themselves right to the bodies of ocean animals.
Fungi are very small, but other living things in the ocean are even tinier,
some so small that they are made of only one cell each. Let's narrow in on the last kingdom;
bacteria. Bacteria in the ocean are so tiny that most can only be seen under a microscope.
Some kind of ocean bacteria have an unusual feature; they give off light. When bioluminescent
bacteria float freely in the water it can look as if the sea itself is glowing. Other bioluminescent
bacteria live in the bodies of fish, making it appear as if parts of the fish are glowing.
The ocean has always been a place of adventure and mystery for mankind.
As we learn more about the marine life living under its shining waves, we can grow to appreciate
all living ocean creatures from the very largest animals to the microscopic bacteria.