Using a combination of MRI, micro-CT and minimally invasive gene analysis, a team of biologists from the Institut für Evolutionsbiologie und Ökologie at the Rheinische Friedrich-Wilhelms-Universität has discovered a new species of dumbo octopus — named Grimpoteuthis imperator — living in the northern part of the Emperor Seamounts, an undersea mountain chain in the northwestern part of the North Pacific.
The dumbo or finned octopuses are a group of deep-sea-dwelling octopuses that includes around 45 species.
Amongst cephalopods, they constitute relatively rare organisms, despite forming a significant part of the megafauna in deep-sea habitats of the World Ocean down to at least 7,000 m (4.3 miles) depth.
“Their name is based on the flying elephant from the Walt Disney movie of the same name, who is made fun of because of his unusually large ears,” explained Dr. Alexander Ziegler and Dr. Christina Sagorny from the Institut für Evolutionsbiologie und Ökologie at the Rheinische Friedrich-Wilhelms-Universität.
“The fins of the dumbo octopuses are on the sides of the head resemble these elephant ears.”
Current methods used to describe new cephalopod species often require dissection to examine internal organs, which involves damage to or even partial destruction of a specimen and may thus preclude analysis of singular, endangered, rare, or otherwise valuable organisms.
Dr. Ziegler and Dr. Sagorny combined non-invasive methods including digital photography, standardized measurements, MRI and micro-CT, with minimally-invasive tissue sampling for DNA analysis to gather morphological as well as molecular information on a single specimen of dumbo octopus collected from depths of more than 4,000 m (2.5 miles) in the North Pacific Ocean.
The specimen was caught in July 2016 during scientific cruise SO-249 BERING (R/V SONNE) using a chain bag dredge.
The animal was about 30 cm (11.8 inches) in size and was identified as a mature male.
“It was clear to me straight away that we had caught something very special,” the researchers said.
Using the novel combination of non-invasive and minimally invasive techniques allowed the scientists to describe the specimen without damaging it.
They were able to identify details including shell and gill shape, digestive tract morphology, as well as more minute structures such as the nervous system and sensory organs, but also morphological characters so far not used in the description of octopus species, such as the shape of the systemic heart.
By using micro-CT, they were also able to build the first interactive 3D model of a cephalopod beak.
“The results show that this specimen belongs to the cirrate octopod genus Grimpoteuthis,” the authors said.
“Based on the number of suckers, position of web nodules, cirrus length, presence of a radula, and various shell characters, the specimen is designated as the holotype of a new species of dumbo octopus, Grimpoteuthis imperator.”
“The digital nature of the acquired data permits a seamless online deposition of raw as well as derived morphological and molecular datasets in publicly accessible repositories.”
The discovery of Grimpoteuthis imperator is described in a paper in the journal BMC Biology.
A. Ziegler C. Sagorny. 2021. Holistic description of new deep sea megafauna (Cephalopoda: Cirrata) using a minimally invasive approach. BMC Biol 19, 81; doi: 10.1186/s12915-021-01000-9