While Actinus and his ray-finned multitudes
Were multiplying in the waters wide,
Great Acanthus, son of Chondricthus' broods,
Had built his dynasty on a different tide.
For Acanthus bore no bone within his form—
Only cartilage, that softer living frame
That bends and flexes in the ocean's storm
And serves him better than the rigid came
Of calcified and heavy mineral—
The jaw itself that first evolved from gill
Arches long ago was cartilage, and all
That bone has ever been is cartilage still
Made hard—and some have found that keeping soft
Is gift worth more than hardening to stone:
For cartilage is lighter, heals aloft
More quickly—the shark keeps what others disown.
Acanthus bore two sons of different form:
Great Elasmos who would always bless
The water with his terror in the storm,
And quiet Chimaera, who chose less
Of the open ocean's predatory war
And more of the deep ocean's patient hall—
To find his food where no competitors are
And answer the cold deep's ancient call.
Chimaera's children—ratfish, ghost sharks, deep—
Grew plates for grinding shells upon their snout
And sail-like dorsal spines that while they sleep
Trail venom in the water all about.
In caves of deepest ocean, far below
Where light has never reached and pressure kills
All creatures not adapted, there they go
And live their quiet lives in coldest frills
Of darkness—the most ancient cartilaginous
Remaining, little changed from ancient form,
Who find their food in slowest, painstaking
Examination of the ocean floor.
But Elasmos was built for open speed—
He split his children into those who flew
Across the open water in their creed
Of hunting and those who spread out and grew
Flat to the bottom in a different art:
Great Selachios, the sharks who cut the blue
With every streamlined body shaped in part
By nothing but the need to cut through
The water fast and feel the prey ahead—
No equal in the sea for any kind
Of predatory mastery has led
A creature to such perfection of design.
For sharks replaced their teeth in endless rows
That marched from front to back like factory-line—
Each tooth that fell was followed as it goes
By the next one ready, predesigned.
No cavity, no toothache, no decay—
A dozen rows of teeth behind the one
That does the work, and when that falls away
Another takes the place before the sun
Has moved a hand's-breadth in the sky above:
The shark cannot run out of teeth to spare,
And every tooth is sharp as surgeon's glove
And serrated for the cutting laid bare.
The Carboniferous seas were golden age—
A hundred kinds of shark from every form
Wrote their diversity on history's page
Beneath the coal-swamp ocean's ancient storm.
Great Stethacanthos wore upon the stage
Of coal-swamp seas a dorsal fin transformed
Into a platform bristled and engaged
With tooth-like denticles—a shape that stormed
All understanding of what fins are for:
A flat and ironing-board of texture rough
Atop his back—what evolutionary lore
Produced this shape we cannot say enough
To settle—the fossil record fails
To tell us what that platform would achieve:
Display? Aggression? Some tale
That we must from uncertainty retrieve.
Young Xenacanthos took to freshwater streams
And hunted through the coal-swamp rivers wide
With eel-like body chasing all his dreams
Of prey through every turn and eddied tide.
His double-pointed teeth could grip the scales
Of fish that other sharks could not retain—
A specialist whose freshwater regales
Remind us that the ocean's not the main
And only stage where Selachios' kind
Could build their hungry dynasties and rule:
The river has its predators to find
For those who make the freshwater their school.
From Selachios came Batos—rays and skates—
Who flattened out their bodies to the floor
And hid in sand with patience that awaits
Whatever comes to cross the bottom shore.
Their spiracles on top still breathe the water
When the mouth below is buried deep in sand—
The hidden predator, the ocean's daughter
Who strikes from underneath with venom-gland.
The stingray's barb along the tail's sure line,
The manta ray who filtered the open water
With gill-rakes fine as any sieve's design—
Each found a different way through evolution's order
To serve the heritage of Elasmos' house
In form as different as could ever be
From shark to ray, from predator to grouse
Of plankton-feeder—yet the same at sea
In cartilage and in the six-gill breath,
In the live birth or leather-cased egg-purse,
In the ampullae of Lorenzini's depth
Of sense that reads the ocean's hidden verse
Of electromagnetic field that every
Living creature generates—the shark
Can feel you living, feel your heartbeat merry
In the water from across the dark.
The shark has seen the dinosaurs arise
And fall to ash and memory's cold grave,
Has seen the mammals learn to colonize
The land and sea—and still the shark is brave
Enough to be exactly what it was
In early Carboniferous seas of coal:
A shape so perfect evolution does
Not need to change—the perfect is the whole
Of what the shark already is and was
And always has been since the first one swam.
Honor the ancient predators, because
The oldest answer is the finest exam
Of what endurance looks like over time:
The shark unchanged through every dying age—
The living proof that sometimes the sublime
Comes first and stays first on life's oldest stage.