amphibious centipede:

Description: It was found in Japan and is more than 20cm in length. 

Have you ever seen a jade coloured centipede that is longer than your hand, crawling on two dozen legs and inflicting goosebumps on your skin? 

Centipedes have always caused a feeling of unease in me. They might be crawling on the floor but I feel it’s moving on my flesh..!!..

Well, a newfound species of centipede in Japan has added another amphibious natured creature to the list. 

But let me tell you that it’s only the third amphibious Scolopendra species in the world..!!.. This 20cm long and 2cm wide centipede has become the largest centipede species in Japan and Taiwan. 

A large centipede in the genus Scolopendra was discovered in four areas of the Ryukyu Archipelago (Okinawa) and Taiwan. The huge centipede, about 20 cm long and 2 cm wide (about as thick as an adult thumb), was seen preying on Japan’s largest river shrimp, Macrobrachium japonicum (about 10 cm long). It is one of the largest new species of terrestrial arthropods ever discovered in Okinawa.

This is the world’s third semi-aquatic centipede ever discovered, and the largest species of centipede found in Japan and Taiwan. Genetic analysis clearly confirmed that it is a new species.

This is the first time that Japanese scientists have discovered and named a species in the Scolopendra genus which includes the largest species of centipede in Japan.

Let’s have a detailed knowledge of this record-breaking centipede…

The many-legged arthropod is only the third amphibious centipede from the group Scolopendra, a genus of about 100 known species, to be classified. The team distinguished this animal from other members of the genus in the area through a genetic analysis.

It’s not the largest of Scolopendra—that honor belongs to the aptly named Scolopendra gigantea, a South American centipede that can grow to nearly a foot long. Though, when dealing with such creatures, perhaps a few inches doesn’t really change how you feel about the thing. Others of the genus are known to be venomous, with fangs that deliver a painful bite. But study authors haven’t had a chance to figure out whether this new species is venomous just yet.

Centipedes, with their plate-like exoskeletons, don’t particularly resemble other amphibians like frogs and salamanders. But swimming is a useful adaptation to these hungry, hungry centipedes, which writhe through the water like Bionicle sea snakes. 

Some amphibious animals are able to move seamlessly from walking to swimming, and now scientists think they’ve found out how they do it.

Researchers from Japan, Switzerland and Canada say they have decoded the flexible motor control mechanism underlying how salamanders and centipedes, among others, coordinate their bodies and appendages during this “adaptive locomotion”.

They did it by watching the Chinese red-headed centipede (Scolopendra subspinipes mutilans), which is easy to watch because its homogeneous and segmented body structure puts all the changes on show.

This centipede walks on land by coordinating its many legs, but on entering water folds its legs and swims by bending its body trunk much as an eel does.

The research team, led by Akio Ishiguro from Japan’s Tohoku University, observed intact and nerve transected during this transition and suspected that interactions between the central nervous system, the peripheral nervous system, the body, and the environment could explain it.

They hypothesised that walking or swimming signals generated in the brain are sent posteriorly via distributed neural networks belonging to the central nervous system and located along the body, and that these signals can be overridden by sensory signals felt by the peripheral nervous system of the legs when they touch the ground during walking. 

They then described this multiple-signal mechanism mathematically and reproduced the behaviour of centipedes in different situations through computer simulations.

“This suggests two distinctly different roles of sensory feedback for swimming compared with walking,” says co-author Emily Standen, from Canada’s University of Ottawa. 

“This adds information about how animal nervous systems can integrate and use sensory feedback to display functional locomotion.”

The authors acknowledge some of the limitations in a study that built a highly abstract model based on behavioural experiments and tested it with simulations.

They suggest, however, that the simplicity of the essential control mechanism described in the model “can be a basis for discussing common principles of locomotion control among various animal species whose detailed structures of neural and mechanical systems are different but may operate on similar mechano-sensory feedback systems”.

They also see the potential to help develop robots that can move on various environments by flexibly changing body coordination patterns.

Amphibious animals adapt their body coordination to compensate for changing substrate properties as they transition between terrestrial and aquatic environments. Using behavioural experiments and mathematical modelling of the amphibious centipede Scolopendra subspinipes mutilans, we reveal an interplay between descending command (brain), local pattern generation, and sensory feedback that controls the leg and body motion during swimming and walking.

The elongated and segmented centipede body exhibits a gradual transition in the locomotor patterns as the animal crosses between land and water. Changing environmental conditions elicit a mechano-sensory feedback mechanism, inducing a gait change at the local segment level.

The body segments operating downstream of a severed nerve cord (no descending control) can generate walking with mechano-sensory inputs alone while swimming behaviour is not recovered. Integrating the descending control for swimming initiation with the sensory feedback control for walking in a mathematical model successfully generates the adaptive behaviour of centipede locomotion, capturing the possible mechanism for flexible motor control in animals.

Who’s the newbie? 

The family of Scolopendridae consists of the genus Scolopendra which encompasses giant tropical centipedes. Around 100 species can be found around the world. They are predominantly located in tropical and subtropical countries like North Africa, Southeast Asia, North or Central America and the Mediterranean. 

The newbie is the species of an amphibious, large centipede, recently discovered on the islands in the archipelago of Japan. 

Scientists have been successful in identifying a centipede species after 143 years, on the Ryukyu Islands in Japan.

What’s in the name? 

The newly discovered species of centipede has been given the name Scolopendra Alcyona. The story behind this 20 legged centipede is quite interesting and scary…

The name S.Alcyona has been derived from Alcyona, a cursed woman in Greek mythology. She was cursed by the Gods because she compared herself to the Goddess Hera. Due to the curse, she transformed into a ‘halcyon bird’, now famously known as a Kingfisher. 

The centipede found slithering through the waters had legs of jade-green colour which were comparable with the colour of the legs of a kingfisher. So, this inspired the researchers to name the centipede S.Alcyona. 

The Japanese name is Ryujinomukade which has its roots in mythology. According to the local stories revolving around the Ryukyu Islands, hundreds of years ago people painted their boats with pictures of centipedes on flags to ward off a dragon God named Ryujin. It is believed that it fears the centipede after being bitten once. 

Because centipedes lack the waxy water-resistant cuticle of other arthropods, they are more susceptible to water loss via evaporation. Thus, centipedes are most commonly found in high-humidity environments to avoid dehydration, and are mostly nocturnal.

Centipedes live in many different habitats including in soil and leaf litter; they are found in environments as varied as tropical rain forests, deserts, and caves. Some geophilomorphs are adapted to littoral habitats, where they feed on barnacles.

The discrepancy with others in the family  

While being searched for in Japan, some of the S.Alcyona were found under the stones in streambeds while some escaped their finders by sliding in the water currents. 

Generally, slight variations among the family are helpful to the scientists to differentiate between the species but this centipede was a hard nut to crack. Some of the morphological differences found in deep studies have shown the following things:- 

• There is a spur on the 20th leg pair.
• The specialised legs used for the transfer of sperm to the females are missing in this species.
• Molecular data of the Alcyona has also helped to distinguish. 

Flexible coordination of body movement in amphibious enables adaptive locomotion across changing environments or landscapes. In particular, the transitions between terrestrial and aquatic environments require flexibility of motor control since the physical properties of the substrates are significantly different.

For example, amphibian salamanders swim in water by propagating axial bending waves with their limbs folded along the body trunk, whereas on land they show a quadrupedal gait with a standing wave of body undulation.

Such an adaptive behaviour is achieved by changing the coordination patterns of many degrees of freedom in the body depending on the substrates, and this strategy is widely observed in various amphibious animals, e.g. fish, turtles, and insects.

Decoding the essential control mechanism in amphibious locomotion may lead to understanding the common principles of flexible motor control in amphibious animals, and its applications will help enhance the adaptability of robotic locomotion to environmental changes.

The key to tackling this problem is to capture the interplay between descending commands from the brain, local pattern generating circuits (i.e. central pattern generator [CPG]) and sensory feedback. In the long history of neurobiology of locomotion control, the abovementioned three elements are considered to play important roles, and the independent function of each element has been clarified to some extent.

The interplay between the three, however, mostly remains elusive, as capturing the complexity of interactions require simultaneous measurement of each type of neural activity, which is technically difficult. In fact, very little is known of the inherent neural control mechanisms which generate the adaptive change in body coordination during amphibious locomotion.

For salamanders, amphibious was reported that two distinct locomotor patterns of walking and swimming can be switched in response to the magnitude of descending command from the brain, and the possible neural circuit was modelled and validated by physical robot experiments. These studies, though pivotal, did not address how amphibious animals sense environmental changes, and therefore, it is still unclear to what extent local sensory feedback mechanisms are responsible for switching between different locomotor patterns.

Herein, we focused on the centipede (Scolopendra subspinipes mutilans) as a model animal. Like the salamander, the centipede exhibits completely different body-limb coordination during amphibious locomotion.

amphibious centipede swims in water with a travelling body undulation movement, whereas on land, it walks by propagating a wave of leg movement with less body undulation. Most importantly, the homogeneous and segmented body structure of the amphibious centipede provides a great opportunity to investigate the role of local sensory feedback in switching motor coordination since the elongate, legged body segments of the centipede facilitate the visualization of kinematic changes in the body as the animal crosses between terrestrial and aquatic environments.

In addition, lesion experiments that alter the continuity of neural signals along the animal are much easier to perform compared with fish, tetrapods, and hexapods, all of whom have fewer limbs and less homogeneous structures.

Indeed, it is known that the central nervous system of the amphibious centipede consists of a series of paired segmental ganglia which controls the body and limb motions and centipedes can walk around even when their head, including the brain, is cut off. Therefore, these findings suggest that centipedes might possess decentralized control mechanisms for generating locomotion patterns.

The verdict of the scientist 

The main scientist involved in this research is Katsuyuki Eguchi, an associate professor in the Graduate School of Science at Tokyo Metropolitan University. He is the study co-author in this entire exploration work. 

Though he is enthralled by this successful venture he is more concerned about the loss of such indigenous species of plants and animals. He is worried about the loss of species before scientists and researchers can reach them. 

The main issue is the dwindling population of every species due to their habitat loss. Many such species are still out there which haven’t been identified and rescued. 

About the giant Alcyona centipede, he is worried about the practice and fondness of keeping them as pets. Although they are difficult to nurture and sustain in confinement, still they are much sought after by pet owners.  

The scientists believe that their discovery will motivate and enlighten people about biodiversity and environmental protection. A better future of nature is being expected by the researchers. 

Some lines…  

“Save Nature before it worsens,

Preserve the globe, not after it gets sunken;

Come let’s mend our faults together,

Or face the wrath of the Earth, our preserver…”

Amphibious lifestyle

Some of the S. alcyona centipedes were found under stones in streambeds, or amphibious were seen preying on river shrimp. Other centipedes evaded their would-be captors by diving into the rivers, suggesting that S. alcyona was equally at home in water and on land, according to the study.

Variations between certain physical features in animals can help scientists differentiate between species that are very similar, but such analysis can be tricky when it comes to Scolopendra centipedes, said study co-author Katsuyuki Eguchi, an associate professor in the Graduate School of Science at Tokyo Metropolitan University. 

“Generally speaking, although Scolopendra species are large in body size, there are only a few morphological differences between closely related species,” Eguchi told Live Science in an email.

Scolopendra centipedes also vary greatly in body color within a given species, which can complicate efforts to tell species apart. In the end, a combination of physical features — a spur on the 20th leg pair and the absence of specialized legs for transferring sperm to females — and molecular data identified S. alcyona as a distinct species, Eguchi said.

“The discovery of one of largest new species of terrestrial arthropods in Japan and Taiwan seems to indicate that the Ryukyu Islands are a treasure trove of nature and biodiversity,” Eguchi said. However, the scientists are concerned that plant and animal species that are still undescribed may be lost before researchers can identify them, “due to the alarming speed of the habitat losses.”

amphibious Giant centipedes such as S. alcyona are also much sought-after as pets, though they are extremely difficult to breed and sustain in captivity. Eager collectors for the pet trade could therefore also hasten the decline of these centipedes, Eguchi said in the email.

“We hope that our discovery will increase the momentum for the conservation of Ryukyu’s biodiversity,” he said.

Originally published on Live Science.

Amphibious locomotion of the centipede Scolopendra subspinipes mutilans

Terrestrial locomotion of a centipede was observed on a flat terrain Supplementary Movie . The centipede walked by propagating the wave of leg movement posteriorly. Notably, body undulation was hardly seen during the straight walking. Aquatic locomotion of the centipede in water is shown in Supplementary Movie . The centipede swam with a posteriorly travelling wave of body undulation with the legs folded along the body side except for a few anterior legs that mostly remained unfolded.

–by SAMBHAVI YADAV

Content Writer (Erakina By RTMN)

22.11.2021