Squids can eat as algae, crabs, and other squid. These animals can eat 30 percent more than their body weight.
Squids can eat almost all species of fish, including tuna. Yes, they can eat birds. Researchers have seen squid attacking and eating seagulls. Squids are carnivores that eat clams, algae and many small sea animals. Copepods are really small just 2mm in length. Some are surprisingly tiny—only about 1 inch 2. Others are impressively large, including the colossal squid Mesonychoteuthis hamiltoni , which can grow to be even bigger than the giant squid, reaching 45 feet 14 meters.
These squid species are closely related to snails, clams, and even slugs: they are all mollusks , which are defined by their soft bodies. Some of these soft bodies are encased in hard shells, such as clams and snails, but not the squids. Squids belong to a particularly successful group of mollusks called the cephalopods , which have been around for about million years.
Some ancestors of modern-day squids had shells, such as the ammonites , which ruled the waves million years ago. Of those that are still around, one small group—the nautiluses—has an external shell. The other—which includes squids, cuttlefishes, and octopods—does not, although squids and cuttlefishes have an internal, backbone-like support made of chitin called a pen. Shell or no shell, all cephalopods have well-developed brains and are very active, jet-propelling themselves through the ocean.
Most have ink sacs. And many can change skin color and texture in the blink of an eye. Giant squid are thought to swim in the ocean worldwide, based on the beaches they've washed upon, as shown in the map via Wikimedia Commons.
However, they're rarely found in tropical and polar areas. They commonly wash up on the shores of New Zealand and Pacific islands, make frequent appearances on the east and west sides of the Northern Atlantic, and the South Atlantic along the southern coast of Africa. How long does it take to grow so big? Unlike mammals, including people, and many fish species, cephalopods grow very quickly and die after a short life.
Evidence from statoliths a small mineralized mass that helps squid balance , which accumulate "growth rings" and can be used to measure age, suggests that giant squid live no more than five years -- which means each squid must grow incredibly quickly to reach 30 feet in just a few years!
To grow at such a rate, giant squid must live in areas of the ocean where there is an abundant supply of food to provide enough energy. Smaller than the head of a pin, this arrow squid Doryteuthis plei embryo looks like a miniature adult and is almost ready to hatch!
Depending on the squid species, the development from a fertilized egg to a nearly-hatched larva can take one or several weeks. Talk about pressure! Giant squid males don't use a modified arm hectocotylus to transfer sperm like most squid; instead, the spermatophore sperm packet is expelled from a penis, which sticks out through the funnel and can be as long as the animal's mantle, up to 7 feet long. Once the male finds a female -- whether it happens by chance or by following a chemical signal is unknown -- the male injects sperm packets directly into the female's arms.
The rest of the story from here is mostly guesswork. The sperm could travel through her arms to fertilize the eggs internally. But researchers suspect that the arm-shot of spermatophores triggers the female squid's ovaries to release eggs bound together with jelly, which she holds in her arms. Then the sperm sense the eggs nearby and migrate in that direction to fertilize the eggs. Females then release millions of tiny, transparent fertilized eggs into the water in a jellied clump called an egg mass.
Most are quickly snatched up as food by other marine animals. But a few survive -- and within a few years, they become giant marine predators. Hunting in the deep dark ocean isn't easy, but these cephalopods have adapted to their environment. In addition to their foot-wide eyes, which help them to absorb as much light as possible to glimpse prey, they also have long feeding tentacles.
These tentacles are more than twice their body length, and the squids can shoot out to long distances like a net. This allows these big, comparatively conspicuous squids to sneak up and catch prey.
But what do giant squids eat? Although scientists have not witnessed a giant squid feeding, they have cut open the stomachs of squids washed up on beaches to see what they had eaten recently. Giant squid mostly eat deep water fishes and other squids—including other giant squids.
They also will attack schools of fish from below, quickly ascending into shallower waters to grab a meal before retreating to safer depths away from predators. Once prey is caught by the suckers and teeth on the feeding tentacles, the squid will rein it in and bring it towards its beak with its eight arms. The beak breaks the food down into smaller pieces, and the radula, a tongue-like organ covered in teeth, grinds it down further.
On the opposite end of the size spectrum is the giant squid Architeuthis dux , the largest invertebrate in the world. Females grow as long as 45 feet and males about 33 feet.
Claims of squids as long as 60 feet long have not been substantiated. Scientists know for sure that giant squids feed on other squids and large fish that swim alongside them in the ocean's depths.
Information about the giant squid diet comes from the stomach contents of the only two intact specimens researchers have found to date. Squids use their tentacles to catch other animals.
The tentacular clubs at the end of their tentacles are covered with sharp suckers that latch onto prey. Once a squid has nabbed its quarry, it holds the animal captive with these clubs and its suction-cup-lined arms. Animals such as the grey-headed albatross and the sperm whale the largest of the toothed whales feed almost entirely on squid.
They are also eaten by large fish such as toothfish. Current research involves using statoliths balance organs in the back of the squid head to determine the age of individuals.
Statoliths are composed of increments laid down daily much like annual tree rings. This makes them powerful tools for assessing age, growth rates and hatch dates of key species. Why live in Antarctica? How many people? Physical description Squid are a diverse group of invertebrates animals without backbones. There are approximately 70 species of cephalopods found in the Southern Ocean.
Breeding Most squid complete their life cycle — from tiny planktonic juveniles to mature adults — in approximately one or two years.
0コメント