Angel or devil? Don’t be fooled by its cute appearance, it is actually very ferocious!

In the cold and dark deep sea, a cute little creature lazily flapped its soft wings and danced. Its pure and transparent body exuded an orange-yellow glow, and its chubby body seemed to be wearing a small skirt. It stretched out several tentacles from its head, tightly grasped the shell of the sea butterfly, and quickly sucked out the other's internal organs.

This is a scene from the documentary Planet Earth Season 3. This marine animal, which is no bigger than an adult's little finger, is called the naked sea butterfly. Because of its beautiful appearance, it is also called sea angel, ice sea angel, ice sea elf, etc. And because of its beautiful and ghostly swimming posture, it looks like a swallow flying from the side, so it is also called "angelfish" or "swallow fish".

With their translucent bodies, graceful postures and unique survival strategies, sea angels have become an indispensable part of the marine ecosystem. Today is World Oceans Day, so let's get to know this "angel of the sea".

Ice sea elves unique prey

Sea angels are naked marine snails that live in the ocean at depths of more than 300 meters. From a taxonomic point of view, they belong to the order Pteropoda, class Gastropoda, phylum Mollusca. Gastropods crawl forward using specialized legs on their abdomens, and most of them carry a shell on their backs.

Sea angels do not have a shell on their backs, so the word "naked" belongs to their name; and as a special snail of the order Pteropoda, the sea angels' feet for crawling have evolved into wing-like locomotor organs, which propel their bodies forward by flapping, so the word "butterfly" belongs to their name.

In terms of feeding habits, sea angels are undoubtedly an outlier among gastropod marine animals. Usually, gastropod members prefer to be vegetarians, relying on plants and algae for food. The unique "serrated" structure of their tongue can easily scrape food into small pieces for easy digestion.

Sea angels are typical carnivorous animals. During the hunting process, sea angels use the three pairs of unique tentacles on their heads to hold their prey accurately and firmly. This unique hunting strategy is quite similar to that of squids and cuttlefish, which belong to the same class of gastropods, and demonstrates their unique survival wisdom and ecological role.

The favorite food of sea angels is a species of sea butterfly. The scientific name of sea butterfly is Pteropoda, which belongs to the order Pteropoda. It has a well-developed abdominal foot that looks like a butterfly's wing and carries a translucent shell to "protect" itself.

Sea Butterfly

When sensing the scent of a sea butterfly, the sea angel gracefully spreads its flexible tentacles. Hidden in its head are six huge hook-shaped mouthparts, which are its deadly weapons for catching sea butterflies.

At the critical moment of hunting, the head of the sea angel will cleverly split into two parts, and those sharp hooks will quickly extend, accurately hooking the soft body of the sea butterfly and pulling it out, and then enjoy this delicious meal. This process is similar to the scene of people picking out snail meat with toothpicks in the food stalls on summer nights.

After successfully catching a sea butterfly, the sea angel will first use its flexible tentacles to carefully touch the shell of the prey to confirm whether it is really a sea butterfly. After confirmation, the sea angel will proceed to the next step of the dining process.

Super Ability Extreme Adaptability

Distributed in the waters near the Antarctic and the Arctic, sea angels, which are only two or three centimeters long, have a super ability to perceive the environment, a hermaphroditic reproduction method, and adaptation strategies in extreme marine environments.

Sea angels have no eyes and can only detect prey through chemical senses. This ability allows them to survive in the deep sea where light is dim and the environment is complex. They can also sense the movement of water currents. Once they sense changes in the water currents, they will swim away quickly to avoid being captured by natural enemies.

Sea angels are hermaphroditic creatures with two reproductive systems. During the breeding season, each sea angel will find another sea angel to mate with and complete the fertilization process at the same time. This reproductive method makes sea angels highly adaptable and flexible in population reproduction.

The strategies used by sea angels to adapt to extreme marine environments include low temperature, high pressure, and high salinity.

The water temperature in the Antarctic and Arctic oceans is extremely low, and in order to survive in this extreme environment, sea angels have evolved the ability to tolerate low temperatures. Their cell membrane structure is more flexible to prevent rupture caused by low temperatures.

In addition, its strong antifreeze ability comes from the sea butterflies it preys on. Sea butterflies are rich in acylglycerols, which are durable and can be converted into lipids to improve the body's antifreeze performance. After eating sea butterflies, the sea angel's body is also rich in acylglycerols, which prevents it from being frozen into a "popsicle".

Naked sea butterfly encounters sea butterfly. Source: "Planet Earth" column

The deep sea is another extreme environment, characterized by great depth and extremely high water pressure. In order to adapt to this high-pressure environment, the body of sea angels has formed three characteristics in the long-term environmental changes: first, its body structure has become soft and elastic to reduce the damage caused by pressure; second, its cell membrane is also softer and contains rich lipid substances, which can improve the stability of the membrane; third, there is a molecule called "promoter" in the body, which can regulate the pressure in the cell and maintain normal growth and function.

The salinity of the Antarctic and Arctic waters is also relatively high. In order to cope with the negative effects of high salinity on cells, sea angels have evolved special salt excretion mechanisms. They maintain water balance in the body by secreting excess salt and keep the salt concentration inside and outside the cells normal.

Multiple roles are important

Sea angels play multiple roles in the marine ecosystem, including carnivorous predators, key species, environmental adaptors, ecological balance maintainers, and scientific research subjects. These roles not only demonstrate their unique survival strategies, but also have important significance for maintaining the balance of marine ecology.

As a part of the food chain, the existence of sea angels is crucial to maintaining ecological balance. Through the process of predation and being preyed on, sea angels have established a complex ecological relationship network with other organisms. This network not only promotes interdependence and symbiosis between species, but also enhances the stability and resilience of the ecosystem.

Sea angel with open tentacles Source: pinterest

In addition, the unique ecological habits and adaptation strategies of sea angels make them a hot topic in marine biology and ecology research. Through the study of sea angels, scientists can gain a deeper understanding of the structure and function of marine ecosystems, as well as the mechanisms of how organisms adapt and respond to environmental changes.

Although scientists as early as 1774

In the Arctic Sea

Found traces of sea angels

But about its origin and evolution

We are still full of curiosity and questions

Every exploration and discovery will add a new chapter to our further understanding of this colorful ocean world. We look forward to more breakthroughs in human exploration and research of marine ecosystems. Let us work together to protect our blue home and look forward to more mysteries of marine ecology being revealed!

END

Author: Wei Deyong

Member of Guangdong Shenzhen Writers Association

Editor: Dong Xiaoxian