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| Pulau Jong, Jul 2012 |
Year of the Horse: Inside Singapore’s first effort to captive-breed coastal horseshoe crabs
Ang Qing Straits Times, Feb 16, 2026, 05:00 AM
SINGAPORE – For more than a month, a pair of coastal horseshoe crabs have been hooked onto each other under the watch of their Republic Polytechnic (RP) caregivers labouring tirelessly to ensure the species’ survival.
When horseshoe crabs mate, the male grasps the female’s shell with its front claws, externally fertilising the eggs that she releases.
To ensure the best possible conditions for their charges, the students monitor everything from rain – which can dangerously alter the tank’s salinity – to traces of their bead-sized eggs.
This work is part of Singapore’s first effort to captive-breed and study the development of the coastal horseshoe crab.
Ranking among one of the oldest animals on earth, horseshoe crabs are incredibly hardy and have withstood the test of time, said Dr Laura Yap, programme chair of RP’s Diploma in Environmental and Marine Science course. “Unfortunately, it is human-driven disturbances that might now cause their decline.”
Timed with the Chinese zodiac’s Year of the Horse, The Straits Times dives into the race to conserve two native animals with equine-linked names: the horseshoe crab and the seahorse.
The mangrove horseshoe crab and the coastal horseshoe crab – both native species of Singapore – are considered locally vulnerable. This means there are fewer than 1,000 mature individuals estimated in the wild, but more than 250.
The mangrove horseshoe crabs are regularly sighted at the Kranji-Mandai mudflats, Sungei Buloh Wetland Reserve and even at the Pasir Ris mangrove. Coastal horseshoe crabs have been spotted mating at Changi Beach Park and East Coast Park.
By foraging, horseshoe crabs stir up sand and mud, releasing trapped nutrients. Their eggs are also food for migratory birds.
However, horseshoe crab sightings are becoming rarer. “People aged 60 and above have shared stories with our team about how they could easily find horseshoe crab eggs as children,” Dr Yap said. “That suggests that horseshoe crabs were more numerous in Singapore in the past.”
The coastal species is particularly difficult to track. Unlike their mangrove cousins, which typically stay in one muddy habitat throughout their lifetime, coastal horseshoe crabs are migratory and spend most of their lives hidden on the seafloor.
This mobility makes them highly susceptible to Singapore’s expanding shoreline, which changes due to land reclamation and other coastal developments. This interrupts the links that coastal horseshoe crabs need between marine habitats.
Launched in 2024, Dr Yap and her team’s research into captive-breeding coastal horseshoe crabs and their life stages will break new ground.
“Many of the developmental stages and the behaviour of this species are still unknown, such as how long it takes for them to reach certain life stages,” said Dr Yap, who specialises in behavioural and conservation ecology.
Her wider effort to research horseshoe crabs since 2015 has already set the milestone of creating a successful protocol for breeding mangrove horseshoe crabs.
The team then moved on to the coastal variety. This has involved hours of observation. On one occasion, the students waited for three hours just to observe the eggs of horseshoe crabs hatching.
“They do a freedom dance when they’re out,” Dr Yap said with a smile. “It’s really very cute.”
So far, the current pair of coastal horseshoe crabs, collected with the National Parks Board’s permission, has produced roughly 1,700 eggs.
These 3mm-wide eggs are divided across three separate tanks to ensure that a single technical failure does not wipe out the entire generation. “We don’t put all our eggs in one basket, literally.”
But the road to adulthood is long. It takes roughly a decade for a horseshoe crab to reach maturity. Mangrove horseshoe crabs have a lifespan of up to 25 years, while their coastal relatives are estimated to live slightly longer at roughly three decades, said Dr Yap.
As the current project nears its September conclusion, the team hopes to secure permits to release the lab-reared juveniles back into the wild.
Going forward, more research is needed to investigate the long-term impact of oil spills on coastal horseshoe crabs, said Dr Yap, a risk that was driven home when an oil spill closed beaches here in 2024.
She said: “Since they burrow and lay their eggs in the sand, we don’t yet know if the oil affected the development of the eggs.”
By June, another understudied horse of the sea is expected to get a helping hand.
Dr Adam Lim, director of Save Our Seahorses Malaysia, told ST that the non-profit organisation plans to collaborate with Singapore researchers and nature groups to document the distribution and diversity of syngnathid fishes, a family of fishes that includes seahorses, in the Republic’s waters.
Three species of seahorses are considered native to Singapore and all of them are deemed critically endangered.
“Seahorses are important to the overall marine food web and ecosystem,” said Dr Lim, a marine biologist. “They are purely carnivorous and prey on the living organisms at the bottom of the sea, keeping their numbers in check.”
The team founded by his late mentor, Mr Choo Chee Kuang, has spent 21 years surveying Malaysia’s waters for seahorses, while educating the public on the animals.
The members recently decided to take their education efforts to companies after realising that white-collar workers aged 18 to 55 with minimal exposure to nature ranked the lowest in awareness of the marine environment.
“With hands-on participation, we seek to close the awareness and exposure gap that is present in society,” said Dr Lim, who noted that only an estimated 50 people in the world specialise in syngnathid fishes. At least six of them are active in the ecology and conservation space of South-east Asia, he added. Singapore does not have a specialist in this field of study.
An aim of the upcoming collaboration is to find a champion for the animals in Singapore.
Said Dr Lim: “Conservation efforts are not just the responsibility of the government, non-governmental organisations or certain individuals. It is a collective effort and participation that will help us move conservation forward in all areas.”
