Giant tortoises now outnumber the human population in the Seychelles

Amazing stuff! From almost extinction to overpopulation! Or a plague of tortoise? 

Yesterday, I blogged here about a 194 year old giant tortoise.

"Giant tortoises now outnumber people in the Seychelles. A new survey puts the Aldabra Atoll tortoise population at nearly 183,000, up from fewer than 1,000 in the 1800s."

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A blind giant tortoise lives and mates to age 194

Amazing stuff! This tortoise also survived European discoverers, explorers and seafarers stopping by at Saint Helena since 1502 AD.

"Current theory suggests that Aldabra tortoises dispersed “out of Africa,” first from the eastern African coast to Madagascar, then to Granitic Seychelles, and lastly to the Aldabra atoll, a UNESCO World Heritage Site now harboring around 100,000 tortoises ..."

"On an island in the South Atlantic Ocean, the world’s oldest known land animal spends his days munching on fresh fruit and veggies, sunbathing, napping, and getting frisky with the other members of his bisexual throuple.

At the ripe age of 194 years old, with an estimated hatching date of 1832, an Aldabra giant tortoise named Jonathan ... Old age has not come without challenges, however. Today, Jonathan is blind from cataracts and has lost his sense of smell. But the years do not appear to have diminished his libido: He still regularly mates with Emma and Frederik, two other, much younger, giant tortoises that reside with him on the island of Saint Helena.

What on Earth is Jonathan’s secret?

To find out, scientists decided to take a look at the old tortoise’s genome, as well as his epigenome—the collection of chemical changes on DNA that act like “on/off” switches for genes. ..."

From the abstract:

"Aldabra giant tortoises (Aldabrachelys gigantea) are exceptionally long-lived. We sequenced the genome and methylome of Jonathan, a 194-year-old Aldabra, to explore the molecular basis of his longevity.

Relative to other giant tortoises (A. gigantea and Chelonoidis abingdonii), Jonathan has unique gene variants in most aging pathways.

Moreover, Jonathan has substantial DNA methylation and methylation entropy changes compared to four other Aldabras ranging in age from a 5-year-old juvenile to older adults.

Notably, we found that lower-entropy regions in Jonathan’s methylome were enriched for the promoters of genes involved in the mitochondrial electron transport chain, and RNA metabolism. This suggests that high-fidelity transcription of the genes in these pathways may be crucial for long-lived species.

Our findings support a model for aging wherein the maintenance of low methylation entropy in gene promoters is coupled to efficient mitochondrial energy production, efficient RNA processing, and efficient genomic repair."

ScienceAdviser

Epigenetic insights into extreme longevity in the world’s oldest terrestrial animal, Jonathan

Jonathan, the tortoise

Nigeria’s Fatal Antivenom Shortfall. Really!

Maybe it is time to systematically and routinely kill some of these snakes and destroy their nesting places!

How about eradication of dangerous snakes?

"The death of a high-profile Nigerian singer from a snakebite has ignited widespread outrage over the country’s inadequate supply of antivenom and the need for a national snakebite strategy ..."

Global Health NOW: Health Crisis in Gaza; and Supporting Breastfeeding Mothers in South Africa

How do snakes go for many months without eating?

Amazing stuff!

"... The trick may be losing the genes that produce ghrelin, a key hormone that regulates appetite, digestion, and fat storage.

The team scanned the genomes of 112 species, seeking changes in the DNA that makes ghrelin, dubbed the “hunger hormone ” because it was once thought to be the key to obesity in humans.

In snakes, chameleons, and toadhead agamas, ghrelin genes were either missing or so warped by mutations they could no longer encode the hormone, the scientists found. When the researchers looked at MBOAT4, an enzyme that makes ghrelin function, they found that it too was lost in snakes, chameleons, and the agamas.

Losing ghrelin and MBOAT4 may have been part of how these ambush predators adapted to a boom-and-bust feeding schedule. Normally, ghrelin can help the body turn fat into energy when food is scarce. Without ghrelin and MBOAT4, the reptiles may be able to hold onto their energy reserves for longer, letting them persist in low power mode for months to a year between meals. ..."

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Gut molecule that blocks ‘hunger hormone' may spur new treatments for diabetes, anorexia (no public access)

Loss of ‘hunger hormone’ has made snakes masters of fasting (no public access)

Alligator Courtship | Natural World: Florida

Recommendable!

A museum in Utah sold a 150-million-year-old dinosaur fossil for $26 million at Sotheby's auction

Not bad! What will this museum do with all that extra money?

"A museum in Utah sold the 150-million-year-old fossil of their juvenile ceratosaurus dinosaur—one of only four fossils of the species ever discovered—for $26 million at auction"

Monday, July 21, 2025 - Join The Flyover

Mountain America Museum of Ancient Life ()

A juvenile specimen of Ceratosaurus nasicornis, one four Ceratosaurus skeletons are known to exist, will be on view at a Sotheby’s exhibition starting in July

How specialized intestinal cells help pythons completely digest the bones of their prey

Amazing stuff!

"... When researchers peered into the intestines of Burmese pythons, they saw cells with narrow, crypt-like structures, which contained particles ... not seen previously in other vertebrates.

To find out how the cells worked ... analyzed intestinal cells from 14 year-old Burmese pythons that had fasted for three weeks before being fed one of three diets: a normal diet of whole rodents, a low-calcium diet of de-boned prey, or deboned rodents that had been injected with calcium.

When the pythons were fasting or fed a boneless meal, the crypts in their intestinal cells were narrow and empty;

snakes that ate whole rodents or boneless rodents with added calcium had crypts chock-full of large calcium, phosphorus, and iron particles.

These crypts, the researchers say, may help the snakes deal with excess calcium after eating large animals with many bones. Surprisingly, pythons that ate whole rodents did not have any bone fragments in their droppings, suggesting that they had all been completely dissolved. ..."

From the abstract:

"Burmese pythons, Python molurus bivittatus, digest the skeleton of their prey; this must result in a high amount of calcium and phosphorus passing through the intestinal lining. To determine how Burmese pythons can process this ion influx, the effects of different nutritional diets were examined in juveniles reared in captivity using three different diets: 

a normal diet with calcium and phosphorus provided from entire rodents;

a low-calcium and phosphorus diet using rodents with no bones (‘boneless prey’); and a calcium-rich diet composed of boneless rodents supplemented with calcium carbonate (CaCO3) through intraperitoneal injections inside the prey.

The effect of these diets was analysed along the intestinal mucosa using light and electron microscopy techniques ... Blood calcium and hormone levels [parathyroid hormone (PTH) and calcitonin] were also analysed from fasting pythons and snakes repeatedly fed with either a normal prey diet or a low-calcium and -phosphorus diet (boneless rats).

The results revealed the presence of specialised cells in the intestinal epithelium that are involved in the production of calcium and phosphorus particles in fed snakes. These cells have an apical crypt possessing a multi-layered particle made of calcium, phosphorus and iron-rich nucleation elements in the centre.

In fasting snakes, this cell type has empty crypts.

When snakes are fed with boneless prey, particles are not produced by this cell type, although iron elements are located within the crypts.

When calcium supplements are added to a boneless meal, large particles fill the crypts.

When snakes are fed repeatedly with a low-calcium diet, blood calcium level drops while levels of calcitonin, and particularly of those of PTH, increase.

Therefore, Burmese pythons possess a specialised intestinal cell type involved in excreting excess dissolved calcium and phosphorus that originate from the prey and are precipitated as particles that must accumulate in the faeces.

This cell type is also found in other snake species that eat vertebrates (some Boidae and a colubrid) along with a lizard, the Gila monster, Heloderma suspectum. A broader analysis among vertebrates that ingest their prey whole and dissolve the prey skeleton would allow a thorough evolutionary analysis."

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New “bone-digesting” cell type discovered in pythons

Diet-dependent production of calcium- and phosphorus-rich ‘spheroids’ along the intestine of Burmese pythons: identification of a new cell type? (no public access)

A Burmese python devouring an alligator

Why Wasn't There A Second Age of Reptiles?

Very recommendable!

How Do Female Snakes Pick a Mate?

Amazing stuff! How to deal with a hundred or so suitors!

The Snake Is The Spearhead of Reptile Evolution, an evolutionary winner

Amazing stuff!

"Roughly 128 million years ago snakes suddenly burst into an abundant existence on Earth, eventually diversifying into the 4,000 or so species we see today.

Yet their prevalence can't be solely attributed to their most obvious characterizing traits: abandonment of limbs and body elongation. While 25 different groups of lizards are limbless, no other type of reptile has reached the explosive level of diversity seen among snakes. ..."

"A study of more than 60,000 museum specimens of snakes and lizards worldwide reveals that snakes stand out alone in the evolution of reptiles. ...

The team of international scientists ... explain that a “burst of innovation in form and function” enabled the ancestors of snakes to move with legless bodies, develop chemical detection systems to find and track prey, and grow flexible skulls to swallow large animals. The changes set the stage for snake diversification and survival, particularly after an asteroid impact wiped out about three-quarters of Earth’s plant and animal species. ...
“Snakes are like the Big Bang ‘singularity’ in cosmology – a dramatic expansion of diversity in species and their ecologies, linked to some event that might have occurred early in the evolutionary history of snakes.” ..."

From the editor's highlights and abstract:

"Editor’s summary

Snakes are important members of today’s ecosystems and, together with lizards, make up one-third of the vertebrate biota. Their iconic status largely comes from their morphology and role as impressive and varied predators. Title et al. looked at the evolution of the group and used a large number of natural history diet observations to explore their role in ecosystems. They found that a pulse of evolutionary innovation that occurred at the origin of snakes more than 150 million years ago led to an expansion of diet in squamate reptiles, which had cascading impacts on ecosystems that persist today. ...

Abstract

Snakes and lizards (Squamata) represent a third of terrestrial vertebrates and exhibit spectacular innovations in locomotion, feeding, and sensory processing. However, the evolutionary drivers of this radiation remain poorly known. We infer potential causes and ultimate consequences of squamate macroevolution by combining individual-based natural history observations (>60,000 animals) with a comprehensive time-calibrated phylogeny that we anchored with genomic data (5400 loci) from 1018 species. Due to shifts in the dynamics of speciation and phenotypic evolution, snakes have transformed the trophic structure of animal communities through the recurrent origin and diversification of specialized predatory strategies. Squamate biodiversity reflects a legacy of singular events that occurred during the early history of snakes and reveals the impact of historical contingency on vertebrate biodiversity."

The Snake Is The Spearhead of Reptile Evolution, But Why? : ScienceAlert

Snakes: An Evolutionary Winner (original news release) Study published in Science reveals a burst in serpentine form and function reshaped vertebrate diversity

The macroevolutionary singularity of snakes

Snakes (red) have far more diverse diets than their close lizard relatives (blues). Each dot represents one of 1,314 species and size indicates diversity of food within species.