Umbrella octopus

The umbrella octopus belongs to a group called Opisthoteuthidae. This name comes from Ancient Greek words meaning "back" and "squid." These animals are pelagic octopuses, which means they live in the open ocean. They are most famous for their unique shape. A web of skin grows between their arms. When they spread these arms out, they look like an open umbrella.

This shape is very important to how they move and stay safe.

The physical structure of the umbrella octopus is quite specialized. They have a broad, U-shaped shell that supports muscles. These muscles control a pair of small fins located on the mantle. The mantle is the main body part of the octopus. These fins are much less developed than fins found in other cirrate families. Because of this, the fins mostly act as stabilizers during swimming. The octopus moves through the water using a medusoid motion. This means they use their arms and webbing to swim. The oral surface stays below the mantle, and the web surrounds the bottom of the mantle.

Umbrella octopuses have interesting ways to protect themselves from danger. One method is a process called ballooning. They extend the web between their arms as far as they can. They also curve the outer edges of their arms inward. This causes the edges to touch the ocean floor. This makes them look like a large, puffed-up balloon. Scientists have observed them holding this specific position for five and a half minutes. Another method is called web-inversion. During this, the octopus turns its arms upward. This causes the oral surface of the web to face outward. They may face the floor or lie on their sides while doing this.

When these octopuses are not defending themselves, they are often resting. They use two different tactics when they are near the ocean floor. The first tactic is called bottom-resting. In this position, the octopus erects its mantle. It curves the edges of its arms inward so only those edges touch the floor. The fins extend out parallel to the bottom to help with balance. The second tactic is called flat-spreading. Here, the octopus spreads its arms and web so they are parallel to the bottom. They keep the edges of their arms curved inward. Their heads point backward at a small angle while the fins stabilize them.

These creatures live in the very deep parts of the ocean. They are typically found at depths between 3,000 and 4,000 meters. They prefer to hover just above the ocean floor. Researchers have found them in the South China Sea. They have also been located in the Clipperton-Clarion Fracture Zone in the Pacific Ocean. In that specific area, they have been found at a depth of about 4,800 meters. Their skin is very delicate. If the outer skin is damaged, white spots will appear on the surface.

Scientists have spent many years studying the taxonomy, or classification, of these animals. The family Opisthoteuthidae used to contain only one genus called Opisthoteuthis. However, researchers recently split the family into different groups. They did this after noticing differences in the enlarged suckers on male specimens. This change moved several groups into a new family called Grimpoteuthidae. This new family includes the genera Grimpoteuthis, Luteuthis, and Cryptoteuthis. The genus Opisthoteuthis remains a major part of the original group.

The history of naming these species is very long. The genus Opisthoteuthis was first described by Verrill in 1883. Since then, many different species have been identified by different scientists. For example, Sasaki named Opisthoteuthis albatrossi in 1920. Collins identified Opisthoteuthis borealis in 2005. Other species include Opisthoteuthis californiana, named by Berry in 1949, and Opisthoteuthis medusoides, named by Thiele in 1915. There are even very recent names, such as Opisthoteuthis carnarvonensis by Verhoeff in 2025. This long list of names shows how much we are still learning about the deep sea.