In laboratory experiments, octopuses can be readily trained to distinguish between different shapes and patterns. They have been seen in what some have described as play: repeatedly releasing bottles or toys into a circular current in their aquariums and then catching them. Octopuses often break out of their aquaria and sometimes into others in search of food.
The largest of the 300+ species of octopods, the giant octopus "Enteroctopus", is large indeed. Mature males average about 50 pounds and females about 33 pounds. Their arm spans are about eight feet. They have even boarded fishing boats and opened holds to get in and eat crabs.
In the UK, cephalopods such as octopuses are regarded as "honorary vertebrates" under the "Animals (Scientific Procedures) Act 1986". This gives them protection not normally given to invertebrates.
Octopods are the only invertebrate which have been definitely shown to use tools. At least four specimens of the veined octopus ("Amphioctopus marginatus") have been seen picking up discarded coconut shells, and then reassembling them to use as shelter.
Octopods are active and intelligent predators, with good eyesight and brains. They eat mostly crabs and some fish.
Octopods have a variety of defences. They use active camouflage and mimicry, controlled by their nervous system. Most can eject black ink clouds to help escape, and some can shed an arm in extreme danger. It wriggles, and attracts the attacker.
When octopods reproduce, males use a specialized arm to put packets of sperm into the female's mantle cavity. Males die within a few months of mating. In some species, the female octopus can keep the sperm alive inside her for weeks until her eggs are mature.
After they have been fertilized, the female lays about 200,000 eggs (this figure dramatically varies between species). The female cares for the eggs, guarding them against predators, and gently blows currents of water over them so they get enough oxygen. The female does not hunt during the one-month period spent taking care of the unhatched eggs, and may ingest some of her own arms for sustenance.
At around the time the eggs hatch, the mother leaves the lair and is too weak to defend herself from predators like cod, often succumbing to their attacks. The young larval octopuses spend a period of time drifting in clouds of plankton, where they feed until they are ready to descend to the ocean bottom, where the cycle repeats.
All octopods for which we have data have a relatively short life expectancy. Some species live for as little as six months. Larger species, such as the North Pacific giant octopus, may live for up to five years under suitable circumstances.
"Reproduction is a cause of death": males can only live for a few months after mating, and females die shortly after their eggs hatch. They neglect to eat during the (roughly) one-month period spent taking care of their unhatched eggs, but apparently they do not die of starvation. A biological explanation of these short lifespans (or rapid ageing) is not agreed at present.
Off the coast of California, marine biologists have watched the same female octopod guarding her eggs for over four years. Their development took a long time because the water 1.4 kilometres down was very cold. They knew it was the same octopod because it had a characteristic scar. The research was done using a remote diving vehicle with cameras, lights and robotic arms.
Byzantine Empire
The Byzantine Empire (or Eastern Roman Empire) was the name of the eastern remnant of the Roman Empire which survived into the Middle Ages. Its capital was Constantinople, which today is called Istanbul. Unlike the Western Roman Empire, the most important language was Greek, not Latin, and Greek culture and identity dominated.
The Byzantine Empire was known to its inhabitants as:
In 324, the Roman Emperor Constantine I moved the capital of the Roman Empire to the city of "Byzantium", and he renamed the city Constantinople. 150 years later, after the city of Rome was slowly taken over by Germanic people during the Migration period, Constantinople was the only remaining capital of the Empire. This Eastern empire had a smaller territory than the original Roman Empire.
The Byzantine Empire tried to take back Rome and Italy from the Germans. Between 530–555 AD, the Byzantines won many battles and took back Rome.
These gains did not last however. More Germans came and eventually Italy and Rome was lost again. Worse was to come when Avar and Slavic peoples came to take modern Bulgaria and Greece from the Byzantines. Gradually, after the 560s the invaders won much of the Balkans. These invaders were later followed by the Bulgarians. The Avars and Bulgarians were both Turkic peoples at first. They ruled over Slavic people called "Sklavinai" and slowly absorbed Slavic language and customs.
After western Rome was captured by Germanic people, the Empire continued to control modern Egypt, Greece, Palestine, Syria and Turkey. However, another Empire, known as the Persian or Sassanid Empire, tried to take these lands for itself. Between 224–628 AD, the Romans and the Persians fought many battles, with many men killed in the fighting. Eventually, the Persians were defeated in modern-day Iraq, near the ancient city of Nineveh in 627 AD, allowing the Byzantines to keep their lands.
After this, another enemy appeared: the Arabs. The Byzantines were economically damaged by the battles with the Persians. They could not withstand the Arabs. Palestine, Syria and Egypt were lost between 635 and 645. However, the Byzantines defended Asia Minor (modern Turkey) and the Arab advance stopped.
In 718 AD, the Arabs were defeated outside Constantinople, ending the Arab threat in the east, but leaving the Byzantine Empire severely weakened. In the west, the Byzantines launched a number of attacks against the Bulgarians. Some of these were successful, others were not and led to the deaths of many emperors. Over time, the Byzantine Empire would became weaker as it loss land to outside invaders.
Between 1007–1014, the ambitious Byzantine Emperor Basil II attacked Bulgaria many times and eventually won a great victory. Later, he fully recaptured Greece, adding it back to the Byzantine Empire. He then went on to conquer Bulgaria, which was completed in 1018.
In the east, the Arabs once again became a threat to the Empire. However, Basil II's attacks won many more victories. Much of Syria was restored to the Empire and Turkey and Armenia were secured. After 1025, the Arabs were no longer a threat to the Byzantine Empire.
After the Byzantine Emperor Basil II died, many unskilled Emperors came to the throne. They wasted the money of the Empire and reduced its army. This meant that it could not defend itself well against enemies if they would attack. Later, the Byzantines relied on mercenaries, soldiers who fought for money and not for their country, so they were less loyal and reliable and more expensive. Because they had mercenaries, military generals were able to rise to power and grab it from the elaborate bureaucracy, a system of administration where tasks are divided by departments.
A large number of people known as the Turks rode on horseback from central Asia and attacked the Byzantine Empire. The Seljuk Empire took all of Turkey from the Byzantines by 1091. However, the Byzantines received help from people in Europe. This help is known as the First Crusade. Many knights and soldiers left to help the Byzantines but also to secure Jerusalem for Christians, which at the time was in Muslim hands.
The Byzantine Empire survived and with the help of the Europeans took back half of Turkey from the Turks, with the other half remaining under the Turks. The Byzantines survived because three good Emperors ruled one after the other, allowing the Byzantines to grow strong again.
After the three good Emperors, the remaining Emperors ruled badly and again wasted a lot of money and soldiers.