* . *
  • About
  • Advertise
  • Privacy & Policy
  • Contact
Tuesday, September 23, 2025
Earth-News
  • Home
  • Business
  • Entertainment
    Caesars Entertainment (CZR): Assessing Valuation After Times Square Casino Setback and Mounting Investor Concerns – simplywall.st

    Caesars Entertainment Faces Times Square Casino Hurdles as Investor Concerns Mount

    Why Hilaria Baldwin Has Found the ‘DWTS’ Process ‘Embarrassing’ At Times – WFXG

    Hilaria Baldwin Opens Up About the Embarrassing Moments on Her ‘DWTS’ Journey

    Harvest Fest 2025 – yadkinripple.com

    Celebrate the Bounty: Harvest Fest 2025 is Coming!

    Fox News Entertainment Newsletter: Kate Middleton stuns during Trump state visit, Brett James dead at 57 – Fox News

    Kate Middleton Stuns During Trump State Visit; Remembering Brett James at 57

    Lara Beitz to headline Oshkosh show with top comedians at Time Community Theater Sept. 27 – Yahoo

    Lara Beitz to Headline Star-Studded Oshkosh Comedy Night on September 27

    Shakespeare (with a twist) in Grand Junction – Yahoo

    Experience Shakespeare Like Never Before in Grand Junction

  • General
  • Health
  • News

    Cracking the Code: Why China’s Economic Challenges Aren’t Shaking Markets, Unlike America’s” – Bloomberg

    Trump’s Narrow Window to Spread the Truth About Harris

    Trump’s Narrow Window to Spread the Truth About Harris

    Israel-Gaza war live updates: Hamas leader Ismail Haniyeh assassinated in Iran, group says

    Israel-Gaza war live updates: Hamas leader Ismail Haniyeh assassinated in Iran, group says

    PAP Boss to Niger Delta Youths, Stay Away from the Protest

    PAP Boss to Niger Delta Youths, Stay Away from the Protest

    Court Restricts Protests In Lagos To Freedom, Peace Park

    Court Restricts Protests In Lagos To Freedom, Peace Park

    Fans React to Jazz Jennings’ Inspiring Weight Loss Journey

    Fans React to Jazz Jennings’ Inspiring Weight Loss Journey

    Trending Tags

    • Trump Inauguration
    • United Stated
    • White House
    • Market Stories
    • Election Results
  • Science
  • Sports
  • Technology
    Agentic AI and the future of work: navigating technological promise and the risk of increased automation – Equal Times

    Agentic AI and the Future of Work: Embracing Innovation While Navigating Automation Challenges

    Technology alliance introduces system for stable recycling quality – RECYCLING magazine

    Innovative Technology Alliance Unveils Breakthrough System for Consistent Recycling Quality

    Pepper Pike council considers upgrading technology for streaming meetings, remote meeting participation – Cleveland.com

    Pepper Pike Council Explores Upgrading Technology for Enhanced Streaming and Remote Participation

    How Michelin Uses Technology to Rethink Tire Manufacturing: Interview – Motor1.com

    How Michelin’s Tech-Driven Revolution Is Transforming Tire Manufacturing

    Analysts Offer Insights on Technology Companies: Avnet (AVT), Nvidia (NVDA) and Atlassian (TEAM) – The Globe and Mail

    Experts Share Key Insights on Avnet, Nvidia, and Atlassian’s Future Prospects

    Top Technology Executives Recognized at the 2025 Carolina CIO ORBIE Awards – Yahoo Finance

    Celebrating Excellence: Top Technology Executives Honored at the 2025 Carolina CIO ORBIE Awards

    Trending Tags

    • Nintendo Switch
    • CES 2017
    • Playstation 4 Pro
    • Mark Zuckerberg
No Result
View All Result
  • Home
  • Business
  • Entertainment
    Caesars Entertainment (CZR): Assessing Valuation After Times Square Casino Setback and Mounting Investor Concerns – simplywall.st

    Caesars Entertainment Faces Times Square Casino Hurdles as Investor Concerns Mount

    Why Hilaria Baldwin Has Found the ‘DWTS’ Process ‘Embarrassing’ At Times – WFXG

    Hilaria Baldwin Opens Up About the Embarrassing Moments on Her ‘DWTS’ Journey

    Harvest Fest 2025 – yadkinripple.com

    Celebrate the Bounty: Harvest Fest 2025 is Coming!

    Fox News Entertainment Newsletter: Kate Middleton stuns during Trump state visit, Brett James dead at 57 – Fox News

    Kate Middleton Stuns During Trump State Visit; Remembering Brett James at 57

    Lara Beitz to headline Oshkosh show with top comedians at Time Community Theater Sept. 27 – Yahoo

    Lara Beitz to Headline Star-Studded Oshkosh Comedy Night on September 27

    Shakespeare (with a twist) in Grand Junction – Yahoo

    Experience Shakespeare Like Never Before in Grand Junction

  • General
  • Health
  • News

    Cracking the Code: Why China’s Economic Challenges Aren’t Shaking Markets, Unlike America’s” – Bloomberg

    Trump’s Narrow Window to Spread the Truth About Harris

    Trump’s Narrow Window to Spread the Truth About Harris

    Israel-Gaza war live updates: Hamas leader Ismail Haniyeh assassinated in Iran, group says

    Israel-Gaza war live updates: Hamas leader Ismail Haniyeh assassinated in Iran, group says

    PAP Boss to Niger Delta Youths, Stay Away from the Protest

    PAP Boss to Niger Delta Youths, Stay Away from the Protest

    Court Restricts Protests In Lagos To Freedom, Peace Park

    Court Restricts Protests In Lagos To Freedom, Peace Park

    Fans React to Jazz Jennings’ Inspiring Weight Loss Journey

    Fans React to Jazz Jennings’ Inspiring Weight Loss Journey

    Trending Tags

    • Trump Inauguration
    • United Stated
    • White House
    • Market Stories
    • Election Results
  • Science
  • Sports
  • Technology
    Agentic AI and the future of work: navigating technological promise and the risk of increased automation – Equal Times

    Agentic AI and the Future of Work: Embracing Innovation While Navigating Automation Challenges

    Technology alliance introduces system for stable recycling quality – RECYCLING magazine

    Innovative Technology Alliance Unveils Breakthrough System for Consistent Recycling Quality

    Pepper Pike council considers upgrading technology for streaming meetings, remote meeting participation – Cleveland.com

    Pepper Pike Council Explores Upgrading Technology for Enhanced Streaming and Remote Participation

    How Michelin Uses Technology to Rethink Tire Manufacturing: Interview – Motor1.com

    How Michelin’s Tech-Driven Revolution Is Transforming Tire Manufacturing

    Analysts Offer Insights on Technology Companies: Avnet (AVT), Nvidia (NVDA) and Atlassian (TEAM) – The Globe and Mail

    Experts Share Key Insights on Avnet, Nvidia, and Atlassian’s Future Prospects

    Top Technology Executives Recognized at the 2025 Carolina CIO ORBIE Awards – Yahoo Finance

    Celebrating Excellence: Top Technology Executives Honored at the 2025 Carolina CIO ORBIE Awards

    Trending Tags

    • Nintendo Switch
    • CES 2017
    • Playstation 4 Pro
    • Mark Zuckerberg
No Result
View All Result
Earth-News
No Result
View All Result
Home Science

Millions of crabs scuttle across this island every year

July 11, 2024
in Science
Millions of crabs scuttle across this island every year
Share on FacebookShare on Twitter

With the onset of the rainy season, Christmas Island transforms. Roads shut down, the forest floor comes alive, and tens of millions of red crabs take over. The remote Australian territory, located about 190 nautical miles south of Indonesia, is host to one of the world’s most singular natural occurrences. There, like clockwork each year, red crabs emerge from their burrows en masse and move to the Indian Ocean, guided by rainfall and lunar cycles. Thick-legged, hard-shelled bodies, about five or fewer inches across, cover the 52 square mile island as they embark from land to sea. 

“It’s a spectacular event that few people get to see,” says Brendan Tiernan, Christmas Island National Park’s senior field program coordinator for threatened species. Tiernan has lived and worked on the island for 17 years, as one of its approximately 1,500 residents. Still, each year, he bears an eager witness to “one of the great animal migrations.” 

Decades of a destructive invasive species put a big dent in the red crab populations and in 2023 an unusually dry year disrupted the crustaceans’ reproductive ritual. Yet despite these setbacks (and thanks to active management), Tiernan says the crabs are currently thriving. In 2015, there were about 45-50 million red crabs on Christmas Island. Now, Tiernan says there are over 100 million. Through their numbers and unique life cycle, they shape their island home. 

Ecosystem engineers

Christmas Island red crabs (Gecarcoidea natalis) are a species with a small range. They’re native to just two places: most live on their eponymous isle and a much smaller population inhabits an archipelago called Cocos Islands about 600 miles southeast. For the majority of the year, the crabs inhabit forests. They’re detritivores, living strictly on the ground and in subsurface burrows where they feed on decaying vegetation as well as young seedlings. 

In parts of Christmas Island where the crabs are numerous, the forest floor is devoid of leaf litter. “It looks like it’s been raked, and it’s potholed like a moon-cratered landscape with their burrows,” Teirnan tells Popular Science. “You end up with a really unusual forest structure where there’s no understory and you can see for miles and miles. It looks like nothing else,” he adds. In other tropical  places, such an empty understory might be a sign of trouble, but on Christmas Island it’s the natural state of things. The crabs dictate their environment. 

Despite their big impact, most of the time the crabs aren’t particularly active or conspicuous. They might breathe air, but they’re still “moisture loving creatures,” Tiernan says. As a result, they spend most of the dry season inside their burrows. But when the rains come, it’s a different story. 

Beach bound

In late October or November, Christmas Island generally gets its first significant rainfall of the coming wet season. From there, the crabs begin their countdown. They need to make it to the ocean in time to spawn within a few days of the last quarter moon, when the tides are at their gentlest, and least likely to wash away their young. 

Red crabs leave their forest burrows with the initial rainfall and head towards the coast. “It’s millions of crabs crossing roads and walking over cliffs,” says Tiernan. Somehow, the crustaceans are aware enough of the lunar cycle to adjust the speed of their migration to be faster or more leisurely, depending on how long they have before the last quarter moon and neap tide. The mysterious moon-tracking ability means that some years, “they’ll take their time and meander along very slowly. Other years, they have a tight time budget and you’ll just get this roaring stampede as they all race towards the ocean,” he explains.

CHRISTMAS ISLAND - NOVEMBER 23: In this handout image provided by Parks Australia, thousands of red crabs are seen walking in a drain on November 23, 2021 in Christmas Island. The annual migration of red crabs begins with first rains of the wet season on Christmas Island, usually around October or November. Millions of the red crabs make their way across the island to the ocean to mate and spawn. (Photo by Parks Australia via Getty Images )Thousands of red crabs are seen walking in a drain on November 23, 2021 in Christmas Island. Credit: Parks Australia via Getty Images Handout

Males generally make it to the coast first, where they construct mating burrows. When females arrive, Tiernan says they select the “biggest male with the best burrow” that they can find, and the crabs mate. Once mated, the males return to the forest and the females enter the coastal burrows to brood their eggs–about 100,000 each. The gravid crabs exit their burrows soon after the last quarter moon and release their eggs into the ocean in a mass-coordinated, frantic up-and-down dance, at around 4am, a couple of hours before dawn. 

Immediately upon hitting the water, the eggs hatch into wriggling larvae called “megalops.” The crabs stay at this life stage for about four weeks, until they return to land, molted into tiny crablings. Breeding success varies significantly from year-to-year. “Some years we get an incredible number of baby crabs returning. Other years we get absolutely nothing,” Tiernan notes. Why is something of a mystery. Little is known about the marine stage of the crabs’ life cycle, he says. But in successful years, literally trillions of baby crabs make it back to shore in “this big carpet of red.” 

Resilient red tide

Over the last decade, Tiernan says there’s been a spate of massive crabling returns–markedly increasing the population. “It’s a noticeable change across the landscape. There’s more crabs,” he says. Yet for much of recent history, it wasn’t this way. 

The spread of invasive yellow crazy ants in the 1990’s led to “invasional meltdown.” Yellow crazy ants killed crabs by the millions, spraying formic acid in their eyes and joints in a bid to defend their “supercolony” territories, which can span hundreds of acres. Red crab numbers plummeted through the 2000’s and into the 2010’s, as the ants took over the island. In their wake and in the absence of the crabs, sections of forest changed, developing dense understories and deep leaf litter–transforming the fundamental makeup of the habitat and leaving it inhospitable for other animals native to Christmas Island. Pesticide baits helped to manage the ant problem, but also killed more crabs.

But in 2016, the tide began to shift in the crabs’ favor with the introduction of a biocontrol agent. Australia’s national park agency bred and released a teeny tiny wasp. The Malaysian insect counterintuitively doesn’t target the ants, but rather a scale insect that the ants depend on for their food source. Within just a few years, monitoring revealed the wasp was working. Crazy ant numbers were down and crabs began to rebound. “It’s made it much easier for red crabs to migrate and to live on the island without being decimated by the yellow crazy ants,” says Tiernan. 

The war isn’t totally won, he notes. The park is looking into new ways to apply pesticide treatments and additional biocontrols to eliminate even more ants. At the moment, though, things are looking up for the crabs and the whole Christmas Island ecosystem as a result. 

That’s even after last year, where a much-delayed rainy season effectively halted the mega-migration from occurring. The first rains came in February, and the crabs didn’t head to the coast in anywhere near their usual quantities. 

It’s rare, but not unheard of for the crabs to skip a breeding season in accordance with anomalous weather, Tiernan says. It happened once before in 1997 during a particularly intense El Niño event. Plus, Christmas Island’s climate is subject to the Indian Ocean Dipole, an oscillating pattern similar to the El Niño-Southern Oscillation, which can intermittently lead to exceptionally dry and wet years. Some level of irregularity is to be expected. 

However, climate change is set to make things harder for the island and the crabs in the long-term. According to a recent study commissioned by the national park, Tiernan says that Christmas Island is set to have longer dry periods and shorter, more intense wet periods as global warming progresses. If that probability pans out, the red crabs will struggle to stay fed and hydrated through the dry season, and face a more treacherous wet season migration and breeding period. The crustaceans have proved resilient so far, yet there’s no guarantee they make it over the next hurdle. 

At least for this year though, Tiernan expects a good turnout. “There’s no reason why we shouldn’t get a return to an enormous crab migration.”  In a few months time, Christmas Island will be decked all in red once again.

>>> Read full article>>>
Copyright for syndicated content belongs to the linked Source : Popular Science – https://www.popsci.com/science/christmas-island-crab-migration/

Tags: Crab’sMillionsscience
Previous Post

Starter kit: All the gear you need to start training martial arts

Next Post

A hydrogen-powered air taxi flew 523 miles emitting only water vapor

U.S. and Israel against the world as Palestine dominates UN week – Axios

U.S. and Israel against the world as Palestine dominates UN week – Axios

September 23, 2025
Global economic outlook weakens as policy uncertainty weighs on demand – OECD

Global economic outlook weakens as policy uncertainty weighs on demand – OECD

September 23, 2025
Caesars Entertainment (CZR): Assessing Valuation After Times Square Casino Setback and Mounting Investor Concerns – simplywall.st

Caesars Entertainment Faces Times Square Casino Hurdles as Investor Concerns Mount

September 23, 2025
AI Tool Predicts Health Problems in Patients 20 Years Before They Emerge – eWeek

AI Tool Detects Health Issues Two Decades Before Symptoms Appear

September 23, 2025
Germany’s €80B Rearmament Plan Sidelines US Weapons – politicstoday.org

Germany’s €80B Rearmament Plan Sidelines US Weapons – politicstoday.org

September 23, 2025
FOCUS | SCIO holds press conference on promoting high-quality development through high-level ecological & environmental protection – Xinhua

FOCUS | SCIO holds press conference on promoting high-quality development through high-level ecological & environmental protection – Xinhua

September 23, 2025
Researcher on Tylenol-Autism Connection: Not the Best Science – Managed Healthcare Executive

Researcher Questions the Science Behind Tylenol-Autism Link

September 23, 2025
Da Vinci’s Genetic Secrets May Soon Be Revealed by Ambitious DNA Project – ScienceAlert

Unlocking Da Vinci’s Genetic Mysteries: The Ambitious DNA Project Set to Reveal All

September 23, 2025
Eco-Chic Home & Lifestyle Design Market Is Booming Worldwide | Major Giants The Joinery, Emeco, Greenington – openPR.com

Eco-Chic Home & Lifestyle Design Market Is Booming Worldwide | Major Giants The Joinery, Emeco, Greenington – openPR.com

September 23, 2025
Agentic AI and the future of work: navigating technological promise and the risk of increased automation – Equal Times

Agentic AI and the Future of Work: Embracing Innovation While Navigating Automation Challenges

September 23, 2025

Categories

Archives

September 2025
MTWTFSS
1234567
891011121314
15161718192021
22232425262728
2930 
« Aug    
Earth-News.info

The Earth News is an independent English-language daily published Website from all around the World News

Browse by Category

  • Business (20,132)
  • Ecology (832)
  • Economy (853)
  • Entertainment (21,731)
  • General (17,194)
  • Health (9,896)
  • Lifestyle (865)
  • News (22,149)
  • People (855)
  • Politics (863)
  • Science (16,063)
  • Sports (21,352)
  • Technology (15,835)
  • World (837)

Recent News

U.S. and Israel against the world as Palestine dominates UN week – Axios

U.S. and Israel against the world as Palestine dominates UN week – Axios

September 23, 2025
Global economic outlook weakens as policy uncertainty weighs on demand – OECD

Global economic outlook weakens as policy uncertainty weighs on demand – OECD

September 23, 2025
  • About
  • Advertise
  • Privacy & Policy
  • Contact

© 2023 earth-news.info

No Result
View All Result

© 2023 earth-news.info

No Result
View All Result

© 2023 earth-news.info

Go to mobile version