Pectoral Fin

stalk, shadow, swallow
refractive movement
flushing oxygen


Check out the pec…toral fins on that guy!

Where you may expect to find arms and hands on a fish, you can find their pectoral fins. In fact, the warty frogfish (Antennarius maculatus) has pectoral fins that closely resemble human hands which they use to “walk” short distances.

Lionfish are dazzling beasts and use their dramatically sweeping pectoral fins to inspire haute couture (unclear benefit to survival) and also to herd small fish into a corner and then consume them (clear benefit to survival).

The modest pectoral fins of the Moorish Idol (Zanclus cornutus) don’t initially appear to be anything special but these “winglike” fins can oscillate furiously and, when paired with the Idol’s disc-shaped body, help fish whip around corners jutting out of coral reefs.

Remember Nemo with his rounded caudal fin? Well clownfish pectoral fins are round too and make superb fluttering fans that bring fresh water and oxygen to developing eggs.

Whether it’s motion, hunting or parenting, pectoral fin shape and function is remarkably diverse in fishes.

[update: pectoral fins appear to be sensitive to touch in a way similar to human fingertips!]

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Caudal Fin

undulation, whip!
move it east, move it west
a feathered turbine


Are you always on the go, perpetually in motion as you torpedo from one destination to the next? Your inner fish may be a tuna! Now in order to confirm this please look behind you, is your tail shaped like a double-sided scythe?

As one of the ocean’s cruising specialists, tuna possess a tail, or caudal fin, optimized for continuous and rapid travel. Generally speaking caudal fins generate thrust for fishes that move through water by undulating their bodies. The combined movement of the body and caudal region propels cruising tuna forward, launches Chinook salmon away from hangry grizzly bears, and accelerates Northern pike toward the prey they are lurking.

But not all caudal fins look the same. Tuna have lunate caudal fins that attach to the body at a narrow bridge (i.e. narrow necking) which reduces drag and maximizes thrust. In contrast, Nemo the clownfish has a round caudal fin that is attached to his body by a wide bridge. Of course Nemo isn’t traversing an ocean at rocket speeds but instead must maneuver through anemones and corals.

What fins do coral reef fish rely on to navigate through their complex habitats? I’ll save that for another tail…err…tale.

Smolting

coloured mosaic
meet me there – or meet me here
silenced hues of blue


Each spring beneath the gravel of freshwater rivers in British Columbia baby salmon (or fry) start to stir. They wiggle their little bodies out from under the stones and hang out close to home until they’re ready for their seaward journey.

Most salmon fry spend 1-2 years feeding and growing nearby home. It’s a simple life for these young fishes, so long as they blend in with the vegetation. It just so happens that fry dress in mottled patterns and vertical stripes that provide camouflage from predators creeping among the cattails and cockleburs. When it is time to head out to the ocean for more serious feasting, juvenile fish undergo an elaborate transformation.

Not to be confused with moulting, smolting refers to the complex physiological, behavioural and morphological changes juvenile salmon undergo prior to leaving freshwater and entering a new, salty world. The gills start to produce small pumps that shuttle salt ions out of the body. Aggressive fish play nice and join schools. Importantly, a smolt’s sense of fashion changes. Dark body markings are replaced with a lustrous, metallic coat now superior for open ocean camouflage. How vogue!

Intertidal

a rolling abode
under the heavens’ mastery
he beckons his lady.


Thanks to the gravitational pull of the moon and sun, intertidal zones are covered during high tide and uncovered during low tide.

Many phenomenal creatures reside among the ebbs and flows. Sea lettuce, armored hairy chitons, goose barnacles, breadcrumb sponges, purple shore crabs, rainbow sea stars…intertidal biodiversity is absolutely remarkable.

For fish, the flooded comfort of high tide is in stark contrast to the exposed desert of low tide. During low tide, some fish stay safe in rock crevices filled with seawater (i.e. tide pools). The plainfin midshipman, a toadfish, lives life more dangerously.

During high tide, males emerge from the ocean depths and burrow under intertidal rocks. Next, these gentlemen produce humming sounds to attract females to their rocks. Females affix their eggs to the underside of the rocks and then vanish into the dark as the tide lowers. The dedicated fathers stay put during low tide and brave desiccation to protect offspring developing under their rocks.

Now go visit your nearest intertidal playground!

Spermatozoon

mechanical cell
father, firewood and flow
marathon comet


Sperm this, sperm that. If you want to sound clever when referring to a single, motile, male gamete then speak spur-mat-uhzohuhn.

A spermatozoon is made of three parts: head, midpiece, flagellum (or tail). The head contains genetic material (i.e. DNA). The midpiece contains energy making cellular factories called mitochondria. The flagellum when cross-sectioned looks like a slice of tomato and contains cable-like structures that bend.

Important information encoded on DNA is transferred to the next generation. Mitochondria produce adenosine triphosphate (ATP or Red Bull for sperm) which fuels the undulation of the flagellum. The movement of the flagellum propels the spermatozoon forward to its final destination, an egg. Two become one in mammals when the sperm head fuses with the egg and in fish when the sperm enters a hole on the egg, the micropyle.

Semelparous

one more mile they said
a thunderous clamour – then
beat, beat, flatline


Pacific salmon and Canadian rapper Drake have something in common; they both live according to YOLO, or you only live once.  I study Pacific salmon and celebrities (though only the former professionally) so I thought this topic would be an excellent first post.

Pacific salmon are semelparous which means they only have a single opportunity to reproduce before death.

Once in a lifetime adult Pacific salmon migrate from the ocean to spawn in the freshwater rivers they were born in. No matter what, these fish need to get home, acquire a mate and have babies. Doesn’t matter if the river you are swimming in is warming, polluted or teeming with ravenous predators and fishing hooks. YOLO. Once the migration starts, senescence kicks in and fish start rapidly “aging” as vital organs shut down. All fish die at the end of the journey. No second chances.

Some salmon die en route to spawning grounds. Some of the salmon that make it to spawning grounds die before doing the deed.

Ultimately, no babies means no fitness for you. Without offspring your genetic material does not exist in the next generation, or the generation after that, and so on.

In contrast, Drake is iteroparous and has multiple opportunities to reproduce before death.