Open Oceans

Yellow-Fin Tuna Eggs

If the hatchlings survive, it will take them two years to become adults. In three years, they could be nearly 2m long and weigh 200 kilograms. Don't live long.

Trigger Fish at Sea Mounts

come to the sea mount to spawn. Eggs are good food

White-tip reef sharks

eat reef fish... but prefer to hunt at night, when the reef fish are sleepy and easier to catch. Rest by day and get cleaned

Floaters

little more than jelly enclosed in membranes but they may drift for vast distances.

One of the Fastest Fish in the Ocean

sailfish

How to Comb Jellies trap their Prey?

sticky, net-like webs: One ill-timed fin stroke could bring certain death to a hatchling fish. There are many kinds of these comb jellies - all of them very effective hunters.

Sea Mounts

submerged mountains whose summits do not break the surface. juvenile fish for their first few months would do well to avoid such places. Adult Fish: promising feeding grounds

Bonitos

Tuna Relatives, searching for still smaller plankton feeders that have been attracted by the bloom.

Adult Yellow-Fin Tuna and Shearwaters Hunting

Tuna are heading directly for the bait ball. Shearwater continue to press their attack unfazed. Tuna move on, leaving the shearwaters When the little tuna start to move away, gradually the bait ball sinks towards safety. The shearwaters follow it down to the very limit of their breath-holding ability At last, even they are forced to leave

What Carries New Tuna Hatchlings?

Vast current systems like immense rivers carry them around the ocean basins.

Problem with Flotsam

Wahoos and other predators check them

Basis of Open Ocean Life

Yellow-Fin Tuna and the other animals and microscopic plants of the plankton

The "Travelling Economy"

A manta ray - immense, 5m across from the tip of one wing-like fin to the tip of the other. it's travelling Economy, wasting as little energy as possible as it glides through the waters of the tropics. Eat Plankton

How does the Ocean support so much life?

A single large piece of flotsam can be the reason why several square miles of open ocean, instead of being empty, will support a fish population of hundreds of tons.

Base of a Sea Mount

As currents sweep towards it, they're deflected up its walls. The water coming from the depths carries both nutrients and plankton to the surface. Where the cold water mixes with warmer water at the surface, there's a shimmering effect - a clear sign that the currents are running strongly.

Storm Petrel Hunting

As they hover facing into the wind, they pick out morsels from near the surface, including eggs.

Sailfish Hunting

Detect vibrations in the water, and search for the cause. Rely on eyesight for their final approach, so they hunt mainly in daylight. When sailfish become excited, they change color, lighting up with blue stripes. Mackerel eyes are sensitive to blue and ultraviolet, these colors confuse them, making them easy to catch.

Sturgeon Fish Mating, and what happens to the eggs

Discharge clouds of eggs and sperm into the water. The manta & others arrive, sweep the water into their mouths and sieve out the eggs. Any surviving eggs will be dispersed

Shearwaters and Dolphins Hunting Mackerel

Dolphin start to hunt, Shearwaters take the air Dolphin have found prey, drive a shoal of small mackerel up towards the surface. Shearwaters become underwater predators themselves by Diving The hunting dolphin prevent the mackerel from escaping downwards Soon, the diving birds outnumber the dolphin

Hammerhead Sharks

During the day, they circle the sea mount looking for small fish at the reef edges...looking for cleaners to rid them of their parasites.

Cory's Shearwaters

Half a million of these birds breed on the Azores every year and scour the nearby ocean for food. There's insufficient wind to support gliding flight, and since flapping is a waste of energy, they sit out the calm, clustered in rafts and riding the gentle swells.

Blue-Fin Tuna Adaptations

Has special blood vessels that enable it to keep its body temperature warmer than the surrounding water. As a result, they can survive in much colder conditions, and they travel thousands of miles away from their spawning grounds in the tropics to hunt in cold seas.

Blue Shark Hunting

Heads for the surface to reheat in the warmer water. As it ascends, it detects the smell of oils and proteins shed into the water by the panicked mackerel. The trail leads both the shark and its attendant pilot fish towards an easy meal.

Remora Fish

Hitchhike with Manta Rays

Sunfish Hygiene

Look for floating kelp plants because here they can find Half-moon fish. The sunfish skin is covered in parasites. The hungry half-moons will help: nip off and eat every parasite they can find. Gulls rest on the floating kelp... and if the sunfish send the right signals, the gulls beaks can dig out the most stubborn parasites.

Hunting in the Summer

Northern Atlantic waters are beginning to warm. The hunting is good here, and by june, predators from southern waters are heading towards the Azores.

What happens to newly-emerged Tuna?

Only a tiny percentage of the developing eggs will survive long enough to hatch. Although they CAN swim, they're still very vulnerable. It will be many weeks before they can swim strongly enough to make any real headway in the ocean.

The most Sterile Seas

Open Oceans: "Marine Deserts"

Sardine traveling

Parts of the ocean become rich with food, attracting schools of sardine. They take in water through their mouths and expel it through their gills, sieving out the plankton and funneling it down their throats. The schools travel along the boundaries of the currents, where the plankton is thickest.

Trevally and Blue Maomao

Patrol the surface water near volcanos in search of a meal. These one-kilo fish snap up every morsel of plankton they find. Currents sweeping in from the open ocean bring all kinds of small creatures in dense concentrations.

Pilot Whales

Pilot whales normally hunt in small family groups, but in mid-summer they head for traditional breading grounds in Mediterranean, where they will assemble in super-herds. Males are competing for the favors of the females.

Striped Marlin

Predators that can grow to 3m long. They hunt mainly in daylight, searching the tropical oceans from close to the surface down to depths of 100m. Sometimes their prey gathers in dense shoals, like sardines.

Silky Sharks

Specialize in picking off injured fish and constantly check over the residents around the sea mount.

Feeding on Sardines

Striped Marlin, Juvenile Tuna The noise attracts a giant - a Sei Whale. Such feasts don't last long.

The heaviest bony fish

Sunfish

Sunfish feeding and living

Sunfish spend much of their time at depth, where they feed on jellyfish, but it's cold and dark down there so from time to time, they seek a little rest and recuperation and warm up near the surface.

How do they get nutrients?

The boundaries between these masses of moving water form invisible barriers that can trap plankton and nutrients carried up from the depths.

Spinner Dolphins Hunting

Their skill in tracking food is not a secret. Yellow-fin tuna must be aware of it, for they regularly follow them, but only adult tuna in their second or third year of life have sufficient stamina to keep up with the fast-moving spinners.

Flying Fish Babies

They don't scatter their eggs but lay them on pieces of flotsam, which should serve as a life-raft for their offspring. Any piece of floating debris can serve as a shelter under which baby fish can hide.

Schooling Mackerel

They have already sensed the sonar beams of approaching dolphin. Their only defense is to gather into a ball (shoal). Any fish that stayed out of the shoal would be quickly picked off.

Common Dolphin Hunting

They often travel in huge herds containing many different families. Small groups leave the super-pod and set off on hunting expeditions.

Pacific Spotted Dolphin

They seek parts of the ocean where their food is thickest. Cover as much as 100 miles in a day. Can detect the sound of schooling fish from hundreds of meters away, and start to track down the shoals using sonar

Predators hunting Anchovetta

the small fish can already feel the vibrations of the approaching predators. Formed into a ball, and now they must wait for whatever comes. They've been detected. At first, the sheer scale of the bait ball seems to daunt the predators... but now the bonito arrive and launch the first attack. The speed of attack from Yellow-Fin TUna is so great that groups of anchovetta are splintered from the main fish ball.

How Prey Survive

they Travel