Biology

A Genetic Blueprint for Extreme Longevity

The phylogenetic relationship of ctenophores (comb jellies) to other animals has been a source of long-standing debate.

Until recently, it was thought that Porifera (sponges) was the earliest diverging animal lineage, but recent reports have instead suggested Ctenophora as the earliest diverging animal lineage.

For the past 30 years, researchers have used whole-genome sequencing of organisms to advance their understanding of evolution.

In 2019, paleontologist Karma Nanglu from Harvard University received a finger-sized fossil. The specimen had originated from a fossil-rich stratum of Cambrian limestone in western Utah, and had been kept in a drawer at a Salt Lake City museum for years.

Upon hearing that there could be a very old tunicate, Nanglu expressed excitement interlaced with caution: "That's a group for which there is essentially no fossil record for the entire 500 million years of recorded history."

For more than two years, researchers on board the French expedition ship Tara sailed through the Pacific, stopping at almost 100 coral reefs to take thousands of water and coral samples. The expedition ended in 2018, and the analysis of the massive amount of data collected has taken five years.

Now, the initial results of the data analysis have been published. The findings should help us to better understand the living conditions of corals, to check their health status and to open up new possibilities for nature conservation. 

Cetaceans were not limited by gravity in the buoyant marine environment and evolved multiple giant forms, exemplified today by the largest animal that has ever lived: the blue whale (Balaenoptera musculus).

There are tradeoffs, however, associated with large body size, including a higher lifetime risk of cancer due to a greater number of somatic cell divisions over time.  The largest whales can have ∼1,000 times more cells than a human, with long lifespans, leaving them theoretically susceptible to cancer. 

This makes the otherwise unassuming Arctica islandica clam the longest lived animal species on record, though some corals are probably much older. The clam was initially named Ming by Sunday Times journalists, in reference to the Ming dynasty, during which it was born.

Researchers from Bangor University in North Wales – unaware of the animal’s impressive age – determined the age by drilling through and counting rings on its shell (a technique known as sclerochronology). In the process the clam died.

Reef-building staghorn coral (Acropora cervicornis) was abundant and widespread throughout the Caribbean and Florida until the late 1970s.  The fast-growing coral formed dense thickets in forereef, backreef, and patch-reef environments to depths over 20 m. 

The corals were rescued by the Florida Fish and Wildlife Conservation Commission and NOAA Fisheries after an outbreak of Stony Coral Tissue Loss disease commenced 2014. Previously, little was known about ridged cactus coral reproduction, as no photos, videos, or published studies were ever done on the species' reproductive biology.