By the mid-1950s manatees were already scarce, and monk seals, once common as far north as Galveston, were gone. By the end of the 20th century, up to 90 percent of the sharks, tuna, swordfish, marlins, groupers, turtles, whales, and many other large creatures that prospered in the Gulf for millions of years had been depleted by overfishing.

For all these years you were merely
A smear of light through our telescopes
On the clearest, coldest night; a hint
Of a glint, just a few pixels wide
On even your most perfectly-framed portraits.
But now, now we see you!
Swimming out of the dark - a great
Stone shark, your star-tanned skin pitted
And pocked, scarred after eons of drifting
Silently through the endless ocean of space.
Here on Earth our faces lit up as we saw
You clearly for the first time; eyes wide
With wonder we traced the strangely familiar
Grooves raked across your sides,
Wondering if Rosetta had doubled back to Mars
And raced past Phobos by mistake –
Then you were gone, falling back into the black,
Not to be seen by human eyes again for a thousand
Blue Moons or more. But we know you now,
We know you; you’ll never be just a speck of light again.

I have said that the investigation for which the teeth of the shark had furnished an opportunity, was very near an end... But thereafter, while I was examining more carefully these details of both places and bodies [sedimentary deposits and shells], these day by day presented points of doubt to me as they followed one another in indissoluble connection, so that I saw myself again and again brought back to the starting-place, as it were, when I thought I was nearest the goal. I might compare those doubts to the heads of the Lernean Hydra, since when one of them had been got rid of, numberless others were born; at any rate, I saw that I was wandering about in a sort of labyrinth, where the nearer one approaches the exit, the wider circuits does one tread.

I shall attack Chemistry, like a Shark.
On his plans to set up a joint chemistry laboratory with Davy and Wordsworth in the Lake District.

Nine out of the 10 big fish that were around when I was growing up–the swordfish, the tuna, the marlin, the shark–90 percent of them are gone. If there was that many sharks when I was a kid, there are now this many.

The contest [between the wave and particle theories of light] is something like one between a shark and a tiger, each is supreme in its own element but helpless in that of the other.

The frillshark has many anatomical features similar to those of the ancient sharks that lived 25 to 30 million years ago. It has too many gills and too few dorsal fins for a modern shark, and its teeth, like those of fossil sharks, are three-pronged and briarlike. Some ichthyologists regard it as a relic derived from very ancient shark ancestors that have died out in the upper waters but, through this single species, are still carrying on their struggle for earthly survival, in the quiet of the deep sea.

The most commonly used measure of biodiversity is species richness, which simply means the number of species in one place. But that measure alone does not tell us how healthy an ecosystem is. For example, think of a pristine coral reef and an overfished coral reef. The pristine reef might have dozens of gray reef sharks, whereas the overfished reef could have just one shark left.

The ocean is like a checking account where everybody withdraws but nobody makes a deposit. This is what's happening because of overfishing. Many fisheries have collapsed, and 90 percent of the large fish, sharks and tuna and cod, are gone.

Timorous readers, however, need entertain no feverish fear, on, visiting the Isle of Sheppey, of encountering either wild elephants, crocodiles, sharks, serpents, or man-eating birds of huge dimensions, bearing strange names, and armed with sets of teeth for masticating and digestive purposes, as the author can assure them that they all died out a million or so of years ago, before he undertook to look up their records and write the history of this wonderful little island. Visitors may, however, honestly deplore the absence of the feathery palm trees bearing the luscious date and the lacteous cocoa-nut; but by prosecuting a diligent search they may, at least, be consoled by procuring some of these, rare fossil remains, reminiscent of an incalculable period of time when our particular portion of this hemisphere performed its diurnal revolutions in the immediate zone of the tropics.

We fondly imagine that evolution drives toward higher intelligence. But eagles would think evolution favored flight, elephants would naturally prefer the importance of great strength. Sharks would feel that swimming was the ultimate desirable trait, and eminent Victorians would be quite convinced that evolution preferred Victorians.