Characteristics of Aquatic Life

Characteristics of Marine Life

Common Adaptations of Aquatic Animals to Living in the Ocean

Imagination / Getty Images

  • M.S., Resource Administration and Management, University of New Hampshire
  • B.S., Natural Resources, Cornell University

There are thousands of species of marine life, from tiny zooplankton to enormous whales. Each is adapted to its specific habitat. Throughout the oceans, marine organisms must deal with several problem we avoid on land:

  • Regulating salt intake
  • Obtaining oxygen
  • Adapting to water pressure
  • Dealing with wind, waves, and changing temperatures
  • Getting enough light

There are many ways marine life survive in this environment that is so different from ours.

Salt Regulation

Fish can drink salt water, and eliminate the salt through their gills. Seabirds also drink salt water, and the excess salt is eliminated via the nasal, or “salt glands” into the nasal cavity, and then is shaken, or sneezed out by the bird. Whales don’t drink salt water, instead, they get the water they need from the organisms they eat.


Fish and other organisms that live underwater can take their oxygen from the water, either through their gills or their skin.

Marine mammals need to come to the water surface to breathe, which is why the deep-diving whales have blowholes on top of their heads, so they can surface to breathe while keeping most of their body underwater.

Whales can stay underwater without breathing for an hour or more because they make very efficient use of their lungs, exchanging up to 90% of their lung volume with each breath, and also store unusually high amounts of oxygen in their blood and muscles when diving.


Many ocean animals are cold-blooded (ectothermic) and their internal body temperature is the same as their surrounding environment. Marine mammals, however, have special considerations because they are warm-blooded (endothermic), meaning they need to keep their internal body temperature constant no matter the water temperature.

Marine mammals have an insulating layer of blubber (made up of fat and connective tissue) under their skin. This blubber layer allows them to keep their internal body temperature about the same as ours, even in the cold ocean. The bowhead whale, an arctic species, has a blubber layer that is 2-feet-thick.

Water Pressure

In the oceans, water pressure increases 15 pounds per square inch for every 33 feet of water. While some ocean animals do not change water depths very often, far-ranging animals such as whales, sea turtles, and seals sometimes travel from shallow waters to great depths several times in a single day. How can they do it?

The sperm whale is thought to be able to dive more than 1 1/2 miles below the ocean surface. One adaptation is that lungs and rib cages collapse when diving to deep depths. The leatherback sea turtle can dive to over 3,000 feet. Its collapsible lungs and flexible shell help it stand the high water pressure.

Wind and Waves

Animals in the intertidal zone do not have to deal with high water pressure but need to withstand the high pressure of wind and waves. Many marine invertebrates and plants in this habitat have the ability to cling onto rocks or other substrates so they are not washed away and have hard shells for protection.

While large pelagic species like whales and sharks may not be impacted by rough seas, their prey can be moved around. For example, right whales prey on copepods, which can get spread to different areas during a time of high wind and waves.


Organisms that need light, such as tropical coral reefs and their associated algae, are found in shallow, clear waters that can be easily penetrated by sunlight. Since underwater visibility and light levels can change, whales do not rely on sight to find their food. Instead, they locate prey using echolocation and their hearing.

In the depths of the ocean abyss, some fish have lost their eyes or pigmentation because they are just not necessary. Other organisms are bioluminescent, using light-giving bacteria or their own light-producing organs to attract prey or mates.


Located halfway between the Equator and the North Pole, Romania is the 12th largest country in Europe.

Romania’s terrain is almost evenly divided between mountains, hills and plains.

The Carpathian Mountains

Although not as high as the Alps, the Carpathian Mountains extend over 600 miles in Romania, in the shape of an arch. They are divided into three major ranges: the Eastern (Oriental) Carpathians, the Southern Carpathians (also known as the Transylvanian Alps), and the Western Carpathians. Each of these ranges feature a variety of landscapes, due to the different types of terrain (glacial, karstic, structural, and volcanic).

Romania’s mountains are a great destination for numerous outdoor activities including: climbing, hiking, biking and river-rafting. Some of the most popular ski resorts are Poiana Brasov, Sinaia, Predeal, Vatra Dornei, Lake Balea and Paltinis.

The Danube Delta

Danube River ends its journey of almost 1864 miles through Europe in south-eastern Romania. Here the river divides into 3 frayed branches (Chilia, Sulina, SfГўntu Gheorghe) forming the Danube Delta. It is the newest land in the country, with beaches expanding almost 65 feet into the sea every year.
Overall, the delta is a triangular swampy area of marshes, floating reed islands and sandbanks. It is a UNESCO Biosphere Reservation as well as a protected wetland and natural habitat for rare species of plants and animals.
For more information on the Danube Delta please visit

The Black Sea

The Romanian Black Sea Coast stretches a little over 150 miles. В
The Black Sea is a continental sea, with a low tide and salinity and water temperatures of 77 — 79ЛљF in the summertime.В Its wide, sandy beaches facing east and south-east become a major tourist attraction from May until September.
For tourist information about the Black Sea please visit


98% of the Romania’s rivers spring from the Carpathian Mountains. The upper streams are usually more spectacular, featuring numerous gorges, caves and precipices.

The main rivers in Romania are Mures (473 miles on Romania’s territory), Prut (461 miles on Romania’s territory), Olt (382 miles), Siret (347 miles on Romania’s territory), Ialomita (259 miles), Somes (233 miles on Romania’s territory) and Arges (217 miles). In the east, river waters are collected by Siret and Prut rivers. In the south, waters flow directly into the Danube and in the west most of them are collected by Tisa River.

Europe’s second longest river, the Danube, flows through southern Romania forming part of the country’s frontier with Serbia, Bulgaria and Ukraine. Its blue waters run along 621 miles, from Bazias to the Black Sea. Virtually all of the country’s rivers are tributaries to the Danube, either directly or indirectly.

The Danube is an important water route for domestic shipping, as well as international trade and tourist cruises. The main port, both for trade and tourism, is Constanta, linked to the Danube by a canal build in 1984. Tulcea, Galati, Calarasi, Giurgiu and Drobeta are other important river ports. В The nearest Danube river port to Bucharest is Giurgiu.В Older plans for construction of a 40 miles canal connecting Bucharest with the Danube River are now being re-considered by the Romanian Government. В


There are around 3,500 lakes in Romania, most of them small or medium. В
The largest are the lagoons and coastal lakes on the Black Sea shore, such as Razim (164 sq. miles) and Sinoe (66 sq. miles), or lakes along the Danube bank — Oltina (8.5 sq. miles); Brates (8.1 sq. miles).

Formed at the end of the last Ice Age, the glacial lakes in the Carpathian Mountains are small, but spectacular. Worth mentioning are the glacial lakes in the Retezat Mountains: Zanoaga, the deepest lake in the country (95 feet) and Bucura, the largest (24.7 acres) as well as the lakes located in the Transylvanian Alps (Balea, Capra, Caltun, Podragu).

Lake St. Ana, located in Ciomatu Mare Massif, near Tusnad is the only volcanic lake in Romania, sheltered in a perfectly preserved crater and surrounded by vast fir-tree forests. The lake is solely fed by rain. Therefore, its waters are nearly as pure as distilled water.В

The Red Lake (elevation 3,215 feet), located in the Hasmas Massif, near Bicaz Gorges, is unique in shape and landscape. It is a natural dam lake created in 1837 after a major landslide. The name «Lacul Rosu» (Red Lake) comes from the reddish alluvia deposited by its main tributary.

Flora and fauna

Due to its varied terrain and climate Romania has a diverse flora and fauna.
Over 3,700 species of plants and 33,792 species of animals can be found in Romania. В
Oak, beech, elm, ash, maple and linden made up 71 percent of Romania’s forests while conifers (fir, spruce, pine and larch) account for the remaining 29 percent.

Soil and mineral resources

More than 58.000 square miles — almost two-thirds of the country’s territory — are suitable for agriculture. Arable land accounts for about 40 percent, pastures for 19 percent, and vineyards and orchards represent some 5 percent of the total land area.

Significant oil reserves are concentrated at the foothills of southern and eastern Carpathians. В Oil reserves have also been discovered a few miles away from the Black Sea coast. Large deposits of natural gas are located in the Transylvanian Plateau.

There are important iron ore deposits in Poiana Rusca Mountains, Banat and Dobrogea regions, as well as in Harghita Mountains (Eastern Carpathians). В Most of the nonferrous metal reserves are concentrated in the northwest, particularly in Maramures and Apuseni Mountains. Some of the largest gold deposits in Europe are also located in Apuseni. В Large amounts of pure salt are located at: Slanic, TГ®rgu Ocna, Ocna Mures, Praid and Cacica.

Green Sea Turtle Facts

Chelonia mydas

  • M.S., Resource Administration and Management, University of New Hampshire
  • B.S., Natural Resources, Cornell University

Green sea turtles (Chelonia mydas) inhabit the beaches and offshore locations of 140 countries throughout the world. They are graceful and serene swimmers who migrate thousands of miles through warm subtropical and tropical oceans. All species of these beautiful reptiles are endangered or threatened.

Fast Facts: Green Sea Turtles

  • Scientific Name:Chelonia mydas
  • Common Name(s): Green sea turtle, black sea turtle (in the eastern Pacific)
  • Basic Animal Group: Reptile
  • Size: Adults grow to between 31–47 inches
  • Weight: 300–440 pounds
  • Lifespan: 80–100 years
  • Diet: Herbivore
  • Habitat: In warm subtropical and tropical ocean waters. Nesting occurs in over 80 countries, and they live in the coastal waters of 140 countries
  • Population: Two largest are the Tortuguero population on the Caribbean coast of Costa Rica (22,500 females nest there each season) and Raine Island in the Australian Great Barrier Reef (18,000 females nest).
  • Conservation Status: Endangered


Green sea turtles are distinguished by their streamlined shell or carapace, which covers their entire body except for flippers and head. The adult green sea turtle has an upper shell that blends several colors, gray, black, olive, and brown; its undershell, called a plastron, is whitish to yellow. Green sea turtles are named for the greenish color of their cartilage and fat, not their shells. While sea turtles have fairly mobile necks, they cannot withdraw their heads into their shells.

The flippers of sea turtles are long and paddle-like, making them excellent for swimming but poor for walking on land. Their heads are light brown with yellow markings. The green sea turtle has four pairs of costal scutes, large, hard scales which assist in swimming; and one pair of prefrontal scales located between its eyes.


There are seven recognized species of sea turtles, six of which are in the Family Cheloniidae (the hawksbill, green, flatback, loggerhead, Kemp’s ridley, and olive ridley turtles), with only one (the leatherback) in the family Dermochelyidae. In some classification schemes, the green turtle is divided into two species—the green turtle and a darker version called the black sea turtle or Pacific green turtle.

All sea turtles migrate. Turtles sometimes travel thousands of miles between cooler feeding grounds and warm nesting grounds. A leatherback turtle was tracked by satellite traveling over 12,000 miles for 674 days from its nesting area in Jamursba-Medi beach in Papua, Indonesia to feeding grounds off Oregon. Habitats, diet and the number and arrangement of these scutes are the primary ways to distinguish different sea turtle species.

Habitat and Distribution

Green sea turtles are found throughout the world in warm subtropical and tropical ocean waters: They nest on the beaches of over 80 countries and live on the coasts of 140 countries.

Efforts continue to emphasize the tracking of sea turtle movement using satellite tags to learn more about their migrations and the implications their travels have for their protection. This may help resource managers develop laws that help protect turtles in their full range.

Diet and Behavior

The only herbivore of the extant sea turtle species, green sea turtles graze on seagrasses and algae, which in turn maintains and fortifies the seagrass beds. They migrate long distances between a wide range of broadly separated localities and habitats during their lifetimes. Tagging studies suggest that ones that nest at Ascension Island in the Atlantic Ocean west of Brazil feed on the Brazilian coast, up to 1,430 miles or more away.

Reproduction and Offspring

Sea turtles mature at around age 25–30. The males spend their whole lives at sea, while females mate with the males at sea and then go to selected beaches to dig a hole and lay between 75 to 200 eggs. Female sea turtles may lay several clutches of eggs during a single season, then cover the clutches with sand and return to the ocean, leaving the eggs to fend for themselves. The breeding season occurs in late spring and early summer; the males can breed every year but the females only breed once every three or four years.

After a two-month incubation period, the young turtles hatch and run to the sea, facing attack by a variety of predators (birds, crabs, fish) along the way. They drift at sea until they are about a foot long and then, depending on the species, may move closer to shore to feed.


Climate change, the loss of habitat, and diseases such as fibropapilloma—which causes benign but ultimately debilitating epithelial tumors on the surface of biological tissues—threaten green sea turtles today. Sea turtles are protected by a variety of national and state laws and international treaties, but hunting of live turtles and harvesting of eggs is still underway in many places. Bycatch, the accidental entanglement in fishing gear such as gillnets or shrimp trawling nets, is responsible for hundreds of thousands of turtle deaths and injuries each year. In addition, oceanic pollution and marine debris have been known to disturb and disrupt migration patterns. Vehicle traffic and development of beaches and light pollution of nesting regions disturbs hatchlings, who often go towards the light rather than towards the ocean.

Rising sea temperatures from climate change also affect turtle populations. Because the incubation temperature of eggs determines the animal’s sex, populations in the northern Great Barrier Reef have experienced imbalances of populations with 90 percent or greater females.

Conservation Status

All seven species of sea turtles are listed under the Endangered Species Act. Due to conservation efforts, some populations are recovering: Between 1995 and 2015, the Hawaiian green sea turtle increased at a rate of 5 percent per year.

Physical Characteristics

Adult male and female sea turtles are equal in size.

  • Olive ridleys are the smallest sea turtles. They have carapace lengths of about 51 to 75 cm (20 to 30 in.) and weigh
    33 to 50 kg (73 to 110 lbs.).
  • The Kemp’s ridley has carapace lengths of 52 to 72 cm (20.5 to 28 in.) and weigh 32 to 50 kg (66 to 110 lbs.).
  • Green sea turtle carapaces reach about 78 to 120 cm (31 to 47 in.) long; they weigh 68 to 230 kg (150 to 507 lbs.).
    • The largest individual collected was 1.5 m (5 ft.) long and weighed 395 kg (871 lbs.).
    • The black sea turtle subspecies tends to be smaller with carapace lengths of 59 to 117 cm (23 to 46 in.); they weigh 70 to 120 kg (150 to 265 lbs.).
  • Loggerhead carapace lengths reach about 90 to 105 cm (35 to 41 in.) and they weigh 100 to 180 kg (220 to 397 lbs.).
  • Adult hawksbills have a carapace length of 53 to 114 cm (21 to 45 in.) and weigh about 43 to 91 kg (95 to 201 lbs.).
  • Flatbacks reach carapace lengths of about 81 to 100 cm (32 to 39 in.) and weigh about 60 to 90 kg (132 to 185 lbs.).
  • Mature leatherbacks reach carapace lengths of about 1.2 to 1.8 m (47 to 70 in.) and weigh 200 to 900 kg (441 to 1,984 lbs.).
    • The leatherback is the largest of all living sea turtles.
    • The largest leatherback recorded weighed 916 kg (2,020 lbs.).

Body Shape

Sea turtles are characterized by a large, streamlined shell and non-retractile head and limbs.


Depending on the species, sea turtles’ color range can be olive-green, yellow, greenish-brown, reddish-brown, or black in color. Some green turtles and hawksbills have shells patterned with streaks and blotches of brown or black. Leatherbacks have black carapaces (top shells) dotted with white and white plastrons (bottom shells) with dark splotches.

As its common name implies, the black subspecies (Chelonia m. agassizii) of green sea turtle is typically darker than C. m. mydas.

The green sea turtle gets its name from the color of its body fat (due to its diet of seagrasses and algae), not its shell.

Like many other aquatic animals, sea turtles are countershaded with a dark dorsal (back) and light ventral (lower surface) coloration. Countershading camouflages the turtles from potential predators. When viewed from above, the turtle’s dark back blends in with the ocean depths. From below, the lighter ventral side blends in with the brighter sea surface.


Limbs are flippers adapted for swimming. Sea turtles are awkward and vulnerable on land.

Unlike land turtles, a sea turtle cannot retract its limbs under its shell.

Forelimbs are long and paddle-like.

  • Long digits are fused throughout the flipper.
  • Only one or two claws are present on each fore flipper.
  • A sea turtle swims with powerful wing-like beats of its fore flippers.

Hind flippers serve as rudders, stabilizing and directing the animal as it swims. The hind flippers of some species are quite dexterous at digging nests in the sand.

A sea turtle cannot retract its head under its shell as a land turtle can.

Sea turtles have large upper eyelids that protect their eyes.

Sea turtles do not have an external ear opening.

Like other turtles, sea turtles lack teeth. Jaw shape varies among species. Each species has a jaw shape adapted for its diet.


A sea turtle’s large, bony shell provides protection from predation and abrasion. The dorsal (top) side of the shell is called the carapace.

  • Depending on species, the adult carapace ranges in shape from oval to heart-shaped.
  • In all species except the leatherback, the bony shell is composed of broadened, fused ribs, and the backbone is attached to the carapace.

The ventral (bottom) side of the shell is called the plastron.

In all species except the leatherback, the shell is covered with a layer of horny plates called scutes. Scutes are firm but flexible, not brittle.

Scientists can identify sea turtle species by the number and pattern of scutes.

  • Green sea turtles have 5 central scutes and 4 lateral scutes. The carapace is oval when viewed from above. Adults of the black subspecies have a higher domed carapace.
  • Hawksbill turtles have 5 central scutes and 4 lateral scutes. The scutes overlap and are pointed at the back end. The carapace is elliptical when viewed from above.
  • Loggerhead turtles have 5 central scutes and 5 lateral scutes.
  • Kemp’s ridley turtles have 5 central scutes and 5 lateral scutes. When viewed from above, their carapace is almost completely round.
  • Olive ridleys have 5 central scutes and 6 or more lateral scutes. When viewed from above, their carapace is almost completely round.
  • Flatback turtles have 5 central scutes and 4 lateral scutes. The carapace is rounded when viewed from above and has a flattened profile. The carapace edges of most adult flatbacks are turned up.

The leatherback turtle has a thick and rubbery oil-suffused skin, which is an excellent insulator, allowing this species to venture into much colder water than other sea turtles. The leatherback’s tear-drop shaped carapace is composed largely of cartilage raised into seven prominent longitudinal ridges. A layer of thousands of small dermal bones lies just below the leathery skin.

The shells of adult green and loggerhead turtles are often covered with algae, barnacles, sponges, skeleton shrimp and other ocean animals. Cleaner fish often follow the turtles closely; dining on the shells’ external occupants and helping to keep the turtle shells clean. This cleaning service benefits the turtle by reducing the amount of drag as the turtle swims.

Sexual Dimorphism

Male and female sea turtles do not differ externally until they approach maturity.

Adult males have longer, thicker tails than females, because the male reproductive organ is housed in the base of the tail. In males, the tail may extend beyond the hind flippers.

With the exception of the leatherback turtle, the claws on the fore flippers of sea turtle males are elongated and curved, which may help them grasp a female’s shell during mating.

Atlantic Mackerel Fish Characteristics & Information

The Atlantic Mackerel fish is a species of mackerel which is found in the temperate waters of the Mediterranean Sea, the Black Sea and the northern Atlantic Ocean. It is extremely common in this area, and occurs in huge shoals in the pelagic zone down to about 200 m. The fish is also known by some other names such as Scottish Mackerel, Boston Mackerel, Norwegian Mackerel, Joey, Split or simply as Mackerel.

The Atlantic Mackerel fish spends the warmer months close to shore and near the ocean surface, appearing along the coast in spring and departing with the arrival of colder weather in the fall and winter months. The fish migrates out into deeper and more southern water during the fall and winter (for seeking warmer temperatures). However read some more information about this fish species below.

Atlantic Mackerel Fish Characteristics

The Atlantic Mackerel fish has elongate body with long and pointed snout. Their main body coloration is steel-blue marked with wavy black lines dorsally and silvery-white ventrally. They have 2 spiny dorsal fins, which are spaced far apart. They have 2 pectoral fins, and small caudal and anal fins which are also spaced far apart. Their body tapers down to it’s body length, ending with a large tail fin. They have large eyes which are covered by an adipose eyelid.

Their teeth are small, sharp and conical. They have small scales over their body, with the exceptions of those immediately posterior to the head and around the pectoral fins. And these small scales give these fish a velvet-like feel.

Average body length of the mature Atlantic Mackerel fish is around 30 cm, with maximum recorded body length of 60 cm. And maximum recorded live body weight of the mature fish is 3.4 kg. Photo and info from Wikipedia.

The Atlantic Mackerel fish are mainly feed on zooplankton and small fish.


The Atlantic Mackerel fish generally become mature at their 2 or 3 years of age. They are batch spawner, and both of their eggs and larvae are pelagic. A medium sized female generally lay between 200,000 and 450,000 eggs per season, and numbers of eggs increases with size.

The Atlantic Mackerel fish is mainly used for food. It is tasty and nutritious.

Special Notes

The Atlantic Mackerel fish is a highly commercial fish species. It is generally sought after for it’s meat, which is strong in flavor and high in oil content and omega-3 fatty acids among other nutrients. The fish is generally sold fresh, smoked, salted, frozen, filleted or as steaks.

Average lifespan of the Atlantic Mackerel fish is around or up to 17 years. It is a very popular fish species in some countries, and nearly 1 million tones are caught each year globally. However, review full breed profile of the Atlantic Mackerel fish in the table below.

Atlantic Mackerel Fish | Breed Profile

Cicadas of the Black Sea coast — features and general characteristics

Hemiptera: bugs, aphids and cicadas

The insects in this order are extremely diverse in their size, shape and colour. There are about 6000 described species in Australia, ranging in size from 1 to 110 millimetres in length. The name Hemiptera means ‘half wing’ and all hemipterans share the following features:

Oliarus lubra

  • 2 pairs of wings, although some species may be wingless and others have only forewings. Wings are generally membranous but in some species the forewings may be hardened at the base
  • Piercing or sucking mouthparts appearing as a sharply pointed tube known as a proboscis or rostrum , which extends from the underside of the head
  • Compound eyes of various forms
  • Up to 3 ocelli present
  • Antennae vary and may be either short, or long and conspicuous

The young of hemipterans look like small adults. Some bugs may be mistaken for beetles but can be distinguished by their mouthparts as beetles have mandibulate mouthparts while bugs have sucking/piercing mouthparts.

This order is divided into 3 suborders; true bugs (Heteroptera); hoppers (Auchenorrhyncha) and; aphids, scale insects, lerps and mealy bugs (Sternorrhyncha).

The true bugs have forewings that are hardened at the base and membranous at the tips. They sit flat over the abdomen hiding the membranous hind wings. The head and proboscis can flex forward.

The hoppers have forewings that are uniform in texture and are held like a tent over the abdomen. The head and proboscis point down and back.

Aphids, scale, lerps and mealy bugs usually have soft bodies and most species are wingless. Their heads and proboscis’ point down and back. They often cover themselves with wax or froth which prevents their soft bodies from drying out.

Life Cycle
Hemipterans develop by incomplete metamorphosis and young (or nymphs ) generally resemble small, wingless adults in general structure although their colour and markings may be very different. In some species such as cicadas, the nymphs who are specialised for burrowing appear quite different from the adults. Nymphs will moult 6 to 8 times depending on the species before they attain maturity.

Most species of Hemiptera are plant feeders, sucking sap with many causing considerable damage to crops, ornamental garden plants such as roses, shrubs and trees. Some species are bloodsuckers of mammals and birds while others are predators that feed on other invertebrates, including some pest species and are therefore beneficial to man.

Proboscis of an assassin bug

The proboscis of hemipterans contains cutting blades and a two-channelled tube. Hemipterans feed by cutting into a plant or animal and sending saliva down one of the tubes to begin digestion. The liquid food is then sucked up the other tube.

Almost all hemipterans are terrestrial, although some groups of Heteroptera such as the Gerromorpha and the Nepomorpha inhabit freshwater habitats, living on the surface tension of the water and beneath its surface respectively. Most plant feeding hemipterans are found on the leaves, stems or bark of plants, some species aggregating in enormous numbers, while others can be found living among the roots. Some form protective waxy secretions or hard galls on the leaves and stems of many Australian plants including Acacia and Eucalyptus species.

No comments

Добавить комментарий

Your e-mail will not be published. All fields are required.