Octopus pseudoghost: The mysterious animal is here

Produced by: Science Popularization China

Author: Guo Fei (Yantai University)

Producer: China Science Expo

Deep in the vast ocean, a mysterious kingdom of creatures quietly exists. This dark, cold, high-pressure world is home to many amazing creatures, the most eye-catching of which is the ghost octopus. For a long time, scientists believed that there was only one existing species of the order Ghost Octopus.

However, a recent major discovery by Chinese scientists has changed this perception and revealed another mystery of the deep sea world to us.

Ghost octopus: a "living fossil" in the deep sea

Vampyroteuthis infernalis is a very special deep-sea creature, known as a "living fossil" in the ocean. Its discovery history can be traced back to 1903, when German marine biologist Carl Chun first encountered this strange creature during a deep-sea expedition. The name of Vampyroteuthis infernalis comes from Latin, meaning "vampire squid from hell." Although the name sounds a bit scary, it is actually a relatively gentle creature.

Illustration of a ghost octopus by Karl Chun

(Image source: Wikipedia)

These mysterious marine inhabitants usually live in the middle and deep waters of tropical and subtropical oceans, between 600 and 900 meters deep. The water at this depth is called the "minimum oxygen zone" and the oxygen content is extremely low, but the ghost octopus can survive tenaciously in such a harsh environment, showing amazing adaptability.

The appearance of the ghost octopus is very unique, as if it is a work of nature. Its body is spherical and has eight tentacles, each of which is covered with sensory organs, allowing it to keenly perceive the surrounding environment.

In taxonomy, ghost octopuses belong to the class cephalopoda, but they are neither octopuses nor squids. Instead, they belong to an independent order, the order of ghost octopuses, which contains only one family (ghost octopuses) and one genus (ghost octopuses).

For a long time, scientists believed that there was only one living species of the order Pseudocyptes, which makes Pseudocyptes important in the study of evolutionary biology. They are like living fossils, opening a window for us to understand the evolutionary history of marine life.

The morphology of ghost octopus from different literatures

(Image source: Reference 1)

Discovery of a new species: Octopus pseudoghost

In September 2016, a major discovery changed the scientific community's understanding of the ghost octopus and added a new chapter to this deep-sea legend. While conducting a deep-sea survey in the southeastern waters of Hainan Island, Qiu Dajun and other researchers from the South China Sea Institute of Oceanology, Chinese Academy of Sciences, collected a specimen similar to the ghost octopus but different from it at a depth of 800 to 1,000 meters. This unexpected discovery immediately attracted great attention from researchers, who realized that it could be an important breakthrough.

Pseudo-ghost octopus morphology

(Image source: Reference 1)

The research team immediately conducted detailed morphological observations and genetic analysis on this mysterious specimen. They carefully compared the characteristics of this new specimen with those of the known ghost octopus, trying to find out the similarities and differences between them. Through long-term observation and analysis, scientists gradually became convinced that what they had discovered was not just a variant of the ghost octopus, but a completely new species.

After repeated verification and in-depth research, scientists finally confirmed that this specimen does represent a completely new species. They named it Vampyroteuthis pseudoinfernalis Qiu, Liu & Huang, which means "a species similar to the ghost octopus." This name not only reflects its similarity to the ghost octopus, but also implies the difference between them. Recently, the relevant research results were published online in the Journal of Zoological Systematics.

The discovery of the pseudo-ghost octopus is a major breakthrough. It becomes the second known existing species in the order Ghostoctopus. This discovery enriches our understanding of deep-sea biodiversity.

The difference between the pseudo-ghost octopus and the ghost octopus

Although the ghost octopus and the ghost octopus are very similar in appearance, the researchers found several key morphological differences through careful comparison. These differences seem minor, but are of great significance in taxonomy. They not only prove that the ghost octopus is an independent species, but also provide new clues for our understanding of the adaptive evolution of these deep-sea creatures.

First, the most obvious difference is in their tail morphology. The pseudo-ghost octopus has a distinct pointed tail, a feature not seen in the ghost octopus. The ghost octopus has a relatively rounded rear end without a distinct tail protrusion. This difference in morphology may reflect their different adaptation strategies in swimming and balance.

Secondly, the researchers noticed that there were differences in the shape of the lower horny mandibles of the two species. The lower horny mandibles of the pseudo-ghost octopus were wider and longer, while the lower horny mandibles of the ghost octopus were relatively short. The horny mandibles are important organs for cephalopods to capture and process food, and this difference may suggest that the two species have different feeding habits or hunting methods.

Finally, a subtle but important difference is the location of their light organs. The light organ of the pseudo-ghost octopus is located midway between the fin and the tip of the tail, while the light organ of the ghost octopus is located one-third of the way between the fin and the end of the body. In deep-sea environments, bioluminescence is an important form of communication and camouflage, and the difference in the location of the light organ may reflect their different strategies in using bioluminescence.

Although these morphological differences may seem minor, they together constitute the key features that distinguish the two species. They not only help scientists confirm the status of Pseudo-ghost octopus as a new species, but also provide important clues for in-depth study of the ecological adaptation and evolutionary history of the two species.

Reconstruction of the Rhone River trap ghost octopus (belonging to an extinct group of ghost octopus species)

(Image source: Wikipedia)

From discovery to confirmation of new species

It is not easy to confirm a new species, especially in the field of deep-sea biological research. The particularity of the deep-sea environment makes sampling and research face huge challenges. Therefore, the research team used a variety of scientific methods to verify the uniqueness of the pseudo-ghost octopus to ensure the reliability and scientificity of the research results.

The researchers first conducted a detailed morphological observation of the collected specimens. From external morphology to internal structure, they carefully examined every part of the specimen and compared it comprehensively with the known ghost octopus. This meticulous morphological study is the basis for identifying new species and the starting point for subsequent research.

Next, the research team conducted a lot of literature research. They consulted a large number of historical documents and compared the morphological characteristics of the newly discovered specimens with those of 10 synonyms reported in the past. This step is very important, as it ensures that the newly discovered specimen is not a known synonym, but a truly new species.

However, morphological studies alone are not enough. To further confirm the uniqueness of the pseudo-ghost octopus, the researchers also conducted a detailed genetic analysis. They extracted and analyzed the DNA of the pseudo-ghost octopus and the ghost octopus, paying special attention to two important genetic markers: the mitochondrial COI gene and the nuclear gene 28S rDNA. These genes are often used in the systematic evolutionary analysis of organisms and can reveal the relationship between species.

Through phylogenetic analysis of these genetic data, the researchers found that the pseudo-ghost octopus and the ghost octopus formed two branches with large genetic distance. This finding further supports the conclusion that they are two independent species and provides strong molecular biological evidence for morphological observations.

This multi-angle and multi-method research path not only ensures the reliability and scientificity of the results, but also demonstrates the complexity and rigor of modern biological taxonomy research. It tells us that in scientific research, especially when facing such rare and difficult-to-study deep-sea creatures, it is very important to use a variety of research methods and collect evidence from multiple angles.

Ghost Octopus fossils

(Image source: Wikipedia)

Conclusion

The discovery of Pseudo-ghost octopus is far more than just adding a new name to the biological list. This discovery has greatly enriched our understanding of deep-sea biodiversity and provided new material for studying the evolution and adaptation of deep-sea creatures. By comparing Pseudo-ghost octopus and ghost octopus, scientists may find more clues about how these creatures adapt to the deep-sea environment, providing a new perspective for our understanding of the adaptability and resilience of life.

In addition, as part of the deep-sea food web, understanding the diversity of ghost octopuses is crucial to understanding the entire deep-sea ecosystem. The discovery of each species is like finding a new node in a complex ecological network, which helps us to more fully understand the structure and function of the deep-sea ecosystem.

References:

1. Dajun Qiu, Bilin Liu, Yupei Guo, WASW Lakmini, Yehui Tan, Gang Li, Zhixin Ke, Kaizhi Li, Liangmin Huang. Vampyroteuthis pseudoinfernalis sp. nov. the second extant widespread deep sea squid species of Vampyromorpha (Cephalopoda: Coleoidea). Zoological Systematics, 2024, 49: 246-257.