Studying the super shrimps of the Bay of Bengal
Anika Tabassum, a zoology graduate from the University of Dhaka, recently worked on some extraordinary marine animals that most of us never heard of. The story spirals around her journey with the mantis shrimp
Highlights:
- Mantis shrimps may look like a hybrid between a shrimp and a mantis
- These are burrowing or cave-dwelling and cling to saline waters
- Previously, the existing literature claimed there was only one species in Bangladesh
- The study has resulted in seven additions to the country
- Their predatory strike is among the fastest appendage movements ever reported
We all rejoice over shrimps, for they appease our palate through many delicious dishes. Some of us, who bear a habitual attachment for nature documentaries, might know of the mantis – the shrewd predatory insect always with a praying pose.
But some creatures can appear as a hybrid between a mantis and a shrimp. So much so that the scientists call them mantis shrimps. Regardless of the resemblance, these critters are a standalone group, nowhere near to the land-dwelling insects.
However, mantis shrimps are aquatic, picking the way of the shrimps, and even distantly related to the latter. With an otherworldly outfit, mantis shrimps don several extreme feats. And, there is barely any study on them in Bangladesh.
So, it is not unfair if many of us do not know about them. Zoology graduate Anika Tabassum felt the same, "My story with mantis shrimp started in the final year of my graduation when I had embarked on a remarkable expedition to the Sundarbans. Before that, they were all aliens to me, dull and dead, bottled in the lab and dipped in formalin, and reeked of a pungent smell."
In my freshman year, I also nearly felt the same. The only exception was the pair of the nearly eight-inch dagger that the specimen was brandishing even in a bottled, dead state. And, they cut deep into my memory as much as they should to any fresh zoology student.
The Sundarbans experience
"It was a part of my undergraduate programme. The whole class under the supervision of our teachers visited the mangrove", Anika said. "Our vessel anchored near Dublar Char (Dubla Island). It was winter and we were there to study the catches of the nearshore fishermen", she continued.
Then, the most astonishing thing happened.
Dublar Char, a large mangrove block, is at the outer rim of the Sundarbans, jutting directly into the Bay. Every year in winter, hundreds of fishermen station there for a few months to fish in the surrounding waters.
Their hauls contain creatures of every shape, size, and colour anyone can think of. Some even seem like they are directly from sci-fi movies ascended to the surface from the murky estuaries. "There were many unexplored species. Every one of us was awestruck in that morning", Anika recalled.
"A few of us collected as many specimens as we could. But we were on schedule and soon returned to the vessel. The next couple of hours went in a flurry. We cleaned, processed, photographed, and tagged the specimens till midday", she kept on.
"We had a late breakfast, been tagged with fishy odour for the entire day", she smirked. "But there were some new records, never-been-reported animals. We just knew it."
The expedition not only resulted in a new mantis shrimp to Bangladesh but it also added four more crabs, already featured in the journal Crustaceana. Finally, the effort unfolded into the most extensive work, even for the mantis shrimps in Bangladesh.
Spear, mace and more
Mantis shrimps bear large, paired and powerful raptorial appendages. In addition, they have dozens of appendages. "I had nose-dived into a pile of literature", said Anika, adding that the whole work had required finding the taxonomy keys, dissecting specimens, and glueing eyes to the microscope to observe macro-level body parts.
Generally, these shrimps belong to two broad groups. In one group, the raptorial legs are armed with multiple sharp, cross-faced spines. These are the largest group, and these specialised legs can be 10 to 12 inches. These are often called 'toe-splitters' for they can cause serious injury if mishandled.
The other group, small and less diverse, wears a club-like thickening instead of spines on the hunting legs. These club-bearers are equally unique. Their lightning-fast blows create a cavitation force that can even crack glass!
From the shallows to the abyss
Mantis shrimps mostly prefer shallow waters, living in burrows or caves. According to Anika, these shrimps are "the inhabitants of coral reefs and shallow soft substrates but can occur up to a depth of 1,500 metres".
When asked about the distribution, she responded, "Stomatopods are commonly reported from tropical and subtropical waters".
Currently, there are around 500 species, about a hundred of them living in the Indo-Pacific waters. The number is increasing every year as new species are being discovered from the Tropics.
Where does the tally count stand?
According to the Records of the Australian Museum, Australia has 72 species. The western part of the Bay of Bengal, the neighbouring coast of West Bengal and Odisha, has records of around 50 species – a 2020 study published in the Zootaxa says.
As astonishing and strange as it might sound, in all lexicons of Bangladesh, it is said that the vast maritime water of Bangladesh has only one species. Anika's efforts compiled seven more species to the inventory, now awaiting being featured by a scientific journal.
She described the work as "a scratching of the surface because we barely have any systematic data on our Bay diversity."
Not a smooth journey
Anika repeatedly mentioned the breakdowns that she had to face only with her unbound fascination with mantis shrimps continuously. The jerky journey posed hurdles in the form of limited research facility, unavailability of literature, and discouragement from many peers.
"People insisted that this sort of taxonomic research is of little value", Anika said. But she stood undeterred and stressed. "Someone, in the course of history, studied and discovered these species. If they were able to untangle the mystery of mantis shrimps, then, I, too, should be able to decipher them."
She added, "More research has only led me to realise how deprived these invertebrate groups are. The data deficiency is gaping wide."
Her ultimate reflection seemed thought-provoking as she concluded, "Everything is connected. In the early stages of a research career, one should try to diversify knowledge, broaden the way of thinking and increase engagement in every possible way. That was what I tried with these creatures."
