ICHTHYOSAUR EVOLUTION

During the early Triassic period, ichthyosaurs evolved from a group of unidentified land reptiles that returned to the sea.

They were particularly abundant in the later Triassic and early Jurassic periods before being replaced as a premier aquatic predator by another marine reptilian group, the Plesiosauria, in the later Jurassic and Cretaceous periods.

KELP FORESTS AND CARBON SINKS

Walk along any rocky beach on the Pacific coast after a storm, and you’ll likely find a treasure trove of kelp washed ashore—long ribbons of glossy brown seaweed, glistening in the sunlight like strands of mermaid hair. 

Some pieces stretch for meters, still tangled with small shells and bits of driftwood, while others hold tight, bulbous floats that once kept them buoyant in the underwater forests just offshore. 

When the tide recedes, the air fills with the unmistakable scent of iodine and salt—an ancient perfume carried by the sea.

Kelp is a brown alga, part of the group Phaeophyceae, which evolved roughly 150 to 200 million years ago. 

While kelp itself doesn’t fossilize easily (it’s soft-bodied and decomposes quickly), its ancient lineage can be traced through molecular and microfossil evidence. The earliest relatives of kelp likely appeared in the Jurassic seas, when dinosaurs ruled the land and the oceans teemed with ammonites. 

Microscopic spores and chemical biomarkers in sedimentary rocks tell scientists that brown algae were already photosynthesizing in shallow coastal waters long before the first mammals appeared.

Giant kelp, Macrocystis pyrifera, holds the title for the fastest-growing marine organism on Earth—it can shoot up more than half a meter a day under ideal conditions! 

These towering underwater forests provide shelter and food for thousands of marine creatures, from tiny snails to sea otters, who wrap themselves in the fronds to sleep without drifting away.

Back when I used to scuba drive a lot around Vancouver Island, they were one of my favourite places to explore as those underwater forests were teeming with life.

If you’re beachcombing in British Columbia, Alaska, or California, you might find bull kelp, Nereocystis luetkeana, recognizable by its long, whip-like stipe and single round float. It’s edible and surprisingly tasty. The blades can be dried and used like seaweed chips, while the bulb can be sliced thin and pickled—an oceanic delicacy with a salty, citrusy crunch. 

Other edible seaweeds you might encounter include sugar kelp, Saccharina latissima, which has a slightly sweet flavor, and ribbon kelp, Alaria marginata, often used in soups and salads.

On the foreshore near where I live on Vancouver Island, we have loads of sea lettuce. Sea lettuce, Ulva spp., is one of the ocean’s most vibrant and inviting greens—a delicate, translucent seaweed that looks like bright green tissue paper fluttering in the tide. 

Sea Otter in a Kelp Bed

When you find it washed ashore or swaying just below the surface, it shines an almost neon hue, catching the sunlight in shimmering waves of jade. 

Its thin, ruffled fronds are only a few cells thick, soft to the touch, and often cling to rocks, shells, or docks in intertidal zones where saltwater and freshwater mingle.

Unlike the giant brown kelps that form towering underwater forests, sea lettuce is part of the green algae group (Chlorophyta), sharing pigments more closely related to land plants. 

It grows worldwide in temperate and tropical waters and thrives wherever nutrient-rich water flows—estuaries, tide pools, and shallow bays. When the tide goes out, you might see it draped over rocks like sheets of emerald silk, drying slightly in the sun and releasing a faint, oceanic scent.

Sea lettuce is entirely edible and a favourite among foragers and coastal chefs. Fresh from the sea, it has a mild, slightly salty flavour with a hint of sweetness—similar to spinach or nori. It can be eaten raw in salads, lightly fried until crisp, or dried into flakes and used as a natural salt substitute. 

In many coastal cultures, from Ireland to Japan, Ulva has long been part of traditional cuisine. It’s also rich in vitamins A, C, and B12, along with iron and calcium—proof that sea greens can be as nutritious as they are beautiful. When my little sister was living in County Cork, she shared pictures of folk bathing in tubs of icy sea water and seaweed as a briny health spa treatment.

From a scientific perspective, sea lettuce plays an important ecological role. It provides shelter for small marine creatures like snails, shrimp, and juvenile fish, and it helps absorb excess nutrients from the water, which can help reduce harmful algal blooms. 

However, when too many nutrients enter the ocean—often from agricultural runoff—sea lettuce can grow explosively, creating dense “green tides” that blanket shorelines.

Its lineage stretches deep into the fossil record as well. While soft-bodied algae like Ulva rarely fossilize, green algal relatives appear in rocks over 1.6 billion years old, making them some of Earth’s earliest photosynthesizers.

Beyond their culinary and ecological roles, kelp forests act as powerful carbon sinks, pulling CO₂ from the atmosphere and storing it in the deep ocean. They also buffer coastlines from storms and provide nurseries for fish populations that support global fisheries.

As you stroll the shoreline and your toes brush against that slippery tangle of golden-brown ribbons, remember—you’re touching the living descendant of an ancient lineage that’s been swaying in Earth’s oceans since the age of dinosaurs—beautiful, ancient and tasty!

EOCENE PLANT MATERIAL

GULLS ON THE FORESHORE: T'SIK'WI

A gull cries in protest at not getting his share of a meal

Gulls, or colloquially seagulls, are seabirds of the family Laridae in the suborder Lari. 

The Laridae are known from not-yet-published fossil evidence from the Early Oligocene — 30–33 million years ago. 

Three gull-like species were described by Alphonse Milne-Edwards from the early Miocene of Saint-Gérand-le-Puy, France. 

Another fossil gull from the Middle to Late Miocene of Cherry County, Nebraska, USA, has been placed in the prehistoric genus Gaviota. 

These fossil gulls, along with undescribed Early Oligocene fossils are all tentatively assigned to the modern genus Larus. Among those of them that have been confirmed as gulls, Milne-Edwards' "Larus" elegans and "L." totanoides from the Late Oligocene/Early Miocene of southeast France have since been separated in Laricola.

Gulls are most closely related to the terns in the family Sternidae and only distantly related to auks, skimmers and distantly to waders. 

A historical name for gulls is mews, which is cognate with the German möwe, Danish måge, Swedish mås, Dutch meeuw, Norwegian måke/måse and French mouette. We still see mews blended into the lexicon of some regional dialects.

In the Kwak̓wala language of the Kwakwaka'wakw, speakers of Kwak'wala, of the Pacific Northwest and my family, gulls are known as t̕sik̕wi. Most folk refer to gulls from any number of species as seagulls. This name is a local custom and does not exist in the scientific literature for their official naming. Even so, it is highly probable that it was the name you learned for them growing up.

If you have been to a coastal area nearly everywhere on the planet, you have likely encountered gulls. They are the elegantly plumed but rather noisy bunch on any beach. You will recognize them both by their size and colouring. 

Gulls are typically medium to large birds, usually grey or white, often with black markings on the head or wings. They typically have harsh shrill cries and long, yellow, curved bills. Their webbed feet are perfect for navigating the uneven landscape of the foreshore when they take most of their meals. 

Most gulls are ground-nesting carnivores that take live food or scavenge opportunistically, particularly the Larus species. Live food often includes crab, clams (which they pick up, fly high and drop to crack open), fish and small birds. Gulls have unhinging jaws which allow them to consume large prey which they do with gusto. 

Their preference is to generally live along the bountiful coastal regions where they can find food with relative ease. Some prefer to live more inland and all rarely venture far out to sea, except for the kittiwakes. 

The larger species take up to four years to attain full adult plumage, but two years is typical for small gulls. Large white-headed gulls are typically long-lived birds, with a maximum age of 49 years recorded for the herring gull.

Gulls nest in large, densely packed, noisy colonies. They lay two or three speckled eggs in nests composed of vegetation. The young are precocial, born with dark mottled down and mobile upon hatching. Gulls are resourceful, inquisitive, and intelligent, the larger species in particular, demonstrating complex methods of communication and a highly developed social structure. Many gull colonies display mobbing behaviour, attacking and harassing predators and other intruders. 

Certain species have exhibited tool-use behaviour, such as the herring gull, using pieces of bread as bait with which to catch goldfish. Many species of gulls have learned to coexist successfully with humans and have thrived in human habitats. Others rely on kleptoparasitism to get their food. Gulls have been observed preying on live whales, landing on the whale as it surfaces to peck out pieces of flesh. They are keen, clever and always hungry.

ON THE GLOVE

GROUSE GRIND

HIKING THE CHIEF

CRETACEOUS CAPILANO RIVER

If you are looking for a wee fossil day trip, then a stroll down to the Capilano River is just the thing.

From downtown Vancouver, drive through Stanley Park heading north over the Lion’s Gate Bridge. Take the North Vancouver exit toward the ferries. Turn right onto Taylor Way and then right again at Clyde Avenue. Look for the Park Royal Hotel. Park anywhere along Clyde Avenue.

From Clyde Avenue walk down the path to your left towards the Capilano River. Watch the water level and tread cautiously as it can be slippery if there has been any recent rain. Look for beds of sandstone about 200 meters north of the private bridge and just south of the Highway bridge. The fossil beds are just below the Whytecliff Apartment high rises.

You will see some exposed shale in the area. It does not contain fossil material. The fossils occur only in the sandstone. Interesting, but again, not fossiliferous are the many granitic boulders and large boulders of limestone which may have been brought down by glaciers from as far away as Texada Island. Cretaceous plant material (and modern material) found here include Poplar (cottonwood) Populus sp. Bigleaf Maple, Acer machphyllum, Alder, Alnus rubra, Buttercup Ranvuculus sp., Epilobrium, Red cedar, Blackberry and Sword fern.

LINGULA ANATINA: PRIMATIVE BRACHIOPOD

Lingula anatina — a primitive brachiopod 

One of the most primitive brachiopods is this caramel and cream fellow, Lingula anatina. 

Brachiopods are marine invertebrates with a stalk and two shells connected along a hinge. They are often confused with bivalves such as clams. 

Bivalves have shells on the sides of their bodies. Brachiopods have shells on the top and bottom. As a result, the plane of symmetry in a bivalve runs along the hinge while it runs perpendicular to the hinge in brachiopods. 

Lingula forms are regarded as the most primitive brachiopods and represent the first certain appearance of brachiopods in the fossil records dating back 530 million years. 

Their shells do not have any locking mechanisms. Instead, they rely on complex musculature to move their shells. They are the first known examples of animal biomineralisation — a process whereby living organisms stiffen or harden tissues with minerals. Their shells are composed of calcium phosphate and collagen fibres, characters shared only by evolutionarily distant vertebrates.

Lingulid brachiopods had changed so little in appearance since the Silurian, 443-419 million years ago, they are referred to as living fossils — a term bestowed upon them by Charles Darwin himself.

Photo: Wilson44691 - Own work, Public Domain, https://commons.wikimedia.org/w/index.php?curid=8624418

PLANNING YOUR NEXT STAYCATION: HORNBY ISLAND

Hornby is so many things to so many people. I have avid pottery afficianato friends who go to look through the talented work of local potters. Others swear by the pie. It is off the beaten track and pure heaven.

TAKING IN THE VIEW

One of the most satisfying moments is taking in a sunset after a long days hike. Pure visual poetry. Peaceful, meditative and well-earned. It is a time for reflection on the day, your world, fresh blisters - the gamut!

Have you ever wondered about the colors you see in these moments? What sunlight actually is? Yes, it's light from the Sun but so much more than that. Sunlight is both light and energy. Once it reaches Earth, we call this energy, "insolation," a fancy term for solar radiation. The amount of energy the Sun gives off changes over time in a never ending cycle. Solar flares (hotter) and sunspots (cooler) on the Sun's surface impact the amount of radiation headed to Earth. These periods of extra heat or extra cold (well, colder by Sun standards...) can last for weeks, sometimes months.

The beams that reach us and warm our skin are electromagnetic waves that bring with them heat and radiation, by-products of the nuclear fusion happening as hydrogen nuclei shift form to helium. Our bodies convert the ultraviolet rays to Vitamin D. Plants use the rays for photosynthesis, a process of converting carbon dioxide to sugar and using it to power their growth (and clean our atmosphere!) That process looks something like this: carbon dioxide + water + light energy -->glucose + oxygen = 6 CO2(g) + 6 H2O + photons → C6H12O6(aq) + 6 O2(g) Photosynthetic organisms convert about 100–115 thousand million metric tonnes of carbon to biomass each year, about six times more power than used my us hoomins.

We've yet to truly get a handle on the duality between light as waves and light as photons. Light fills not just our wee bit of the Universe but the cosmos as well, bathing it in the form of cosmic background radiation that is the signature of the Big Bang.

Once those electromagnetic waves leave the Sun headed for Earth, they reach us in a surprising eight minutes. We experience them as light mixed with the prism of beautiful colors. But what we see is actually a trick of the light. As rays of white sunlight travel through the atmosphere they collide with airborne particles and water droplets causing the rays to scatter. We see mostly the yellow, orange and red hues (the longer wavelengths) as the blues and greens (the shorter wavelengths) scatter more easily and get bounced out of the game rather early.

CASTLE PEAK FOSSIL FIELD TRIP

HARRISON LAKE FOSSIL FIELD TRIP

CADOCERAS TONNIENSE

RAIN OR SHINE

EOCENE FOSSIL FIELD TRIP

There was a large downpour of rain that hit Washington State. It resulted in a huge slide at Sumas Mountain that revealed several large exposures of fossil plants, shorebird trackways and the trackways of the large flightless bird Diatryma.

Many of these finds can now be seen at museums in Washington State. While less abundant, evidence of the animals that called this ancient swamp home are also found here. Rare bird, reptile, and mammal tracks have been immortalized in the soft muds along ancient riverways.

HIGH ELEVATION FOSSIL FIELD TRIP

FERGUSONITES HENDERSONAE

A few years ago, I had the very great honour of having a new species of ammonite named after me by paleontologist, Louse Longridge.

Meet Fergusonites hendersonae, a Late Hettangian ammonite from the Taseko Lake area of British Columbia, high up in the Canadian Rockies.

He looks a wee bit like the Cadoceras comma we find in the Mysterious Lake Formation at Harrison Lake but a wee bit thinner and smaller.

KAYAK SAILING THE WEST COAST

JET RANGER FOSSIL FIELD TRIP

CAPILANO RIVER FOSSIL TRIP

There are many fossil sites around Vancouver, British Columbia. Sadly, the volume and preservation of these fossils is far from ideal.

Still, if you are looking for a wee day trip, then a trip to the Capilano River is just the thing. From downtown Vancouver, drive through Stanley Park up and over the Lion’s Gate Bridge. Take the North Vancouver exit toward the ferries. Turn right onto Taylor Way and then right again at Clyde Avenue. Look for the Park Royal Hotel. Park anywhere along Clyde Avenue.

From Clyde Avenue walk down the path to your left towards the Capilano River.  Watch the water level and treat cautiously as it can be slippery. 

Look for beds of sandstone about 200 meters north of the private bridge and just south of the Hwy bridge.  The fossil beds are just below the Whytecliff Apartment high rises.

You will see some exposed shale in the area. It does not contain fossil material. The fossils occur only in the sandstone. Interesting, but again, not fossiliferous are the many granitic boulders and large boulders of limestone which may have been brought down by glaziers from as far away as Texada Island.

Cretaceous plant material found:

• Alder
• Unidentified Bark

What you see on your visit:

• Poplar (cottonwood)  Populus sp.
• Bigleaf maple  Acer machphyllum
• Alder  Alnus rubra
• Buttercup  Ranvuculus sp.
• Epilobrium
• Red cedar
• Blackberry
• Sword fern

FOSSIL CRINOID DETAIL

BERRIES: 366 PROJECT

FOSSIL BEES AND FIRST NATIONS HISTORY

Welcome to the world of bees. This fuzzy yellow and black striped fellow is a bumblebee in the genus Bombus sp., family Apidae. 

We know him from our gardens where we see them busily lapping up nectar and pollen from flowers with their long hairy tongues.

My Norwegian cousins on my mother's side call them humle. Norway is a wonderful place to be something wild as the wild places have not been disturbed by our hands. Head out for a walk in the wild flowers and the sounds you will hear are the wind and the bees en masse amongst the flowers.   

There are an impressive thirty-five species of bumblebee species that call Norway hjem (home), and one, Bombus consobrinus, boasts the longest tongue that they use to feast solely on Monkshood, genus Aconitum, you may know by the name Wolf's-bane.

In the Kwak̓wala language of the Kwakwaka'wakw, speakers of Kwak'wala, and my family on my father's side in the Pacific Northwest, bumblebees are known as ha̱mdzalat̕si — though I wonder if this is actually the word for a honey bee, Apis mellifera, as ha̱mdzat̕si is the word for a beehive.

I have a special fondness for all bees and look for them both in the garden and in First Nation art.

Bumblebees' habit of rolling around in flowers gives us a sense that these industrious insects are also playful. In First Nation art they provide levity — comic relief along with their cousins the mosquitoes and wasps — as First Nation dancers wear masks made to mimic their round faces, big round eyes and pointy stingers. 

A bit of artistic license is taken with their forms as each mask may have up to six stingers. The dancers weave amongst the watchful audience and swoop down to playfully give many of the guests a good, albeit gentle, poke. 

Honey bees actually do a little dance when they get back to the nest with news of an exciting new place to forage — truly they do. Bumblebees do not do a wee bee dance when they come home pleased with themselves from a successful foraging mission, but they do rush around excitedly, running to and fro to share their excitement. They are social learners, so this behaviour can signal those heading out to join them as they return to the perfect patch of wildflowers. 

Bumblebees are quite passive and usually sting in defense of their nest or if they feel threatened. Female bumblebees can sting several times and live on afterwards — unlike honeybees who hold back on their single sting as its barbs hook in once used and their exit shears it off, marking their demise.

They are important buzz pollinators both for our food crops and our wildflowers. Their wings beat at 130 times or more per second, literally shaking the pollen off the flowers with their vibration. 

And they truly are busy bees, spending their days fully focused on their work. Bumblebees collect and carry pollen and nectar back to the nest which may be as much as 25% to 75% of their body weight. 

And they are courteous — as they harvest each flower, they mark them with a particular scent to help others in their group know that the nectar is gone. 

The food they bring back to the nest is eaten to keep the hive healthy but is not used to make honey as each new season's queen bees hibernate over the winter and emerge reinvigorated to seek a new hive each Spring. She will choose a new site, primarily underground depending on the bumblebee species, and then set to work building wax cells for each of her fertilized eggs. 

Bumblebees are quite hardy. The plentiful hairs on their bodies are coated in oils that provide them with natural waterproofing. They can also generate more heat than their smaller, slender honey bee cousins, so they remain productive workers in cooler weather.    

We see the first bumblebees arise in the fossil record 100 million years ago and diversify alongside the earliest flowering plants. Their evolution is an entangled dance with the pollen and varied array of flowers that colour our world. 

We have found many wonderful examples within the fossil record, including a rather famous Eocene fossil bee found by a dear friend and naturalist who has left this Earth, Rene Savenye.

His namesake, H. Savenyei, is a lovely fossil halictine bee from Early Eocene deposits near Quilchena, British Columbia — and the first bee body-fossil known from the Okanagan Highlands — and indeed from Canada. 

It is a fitting homage, as bees symbolize honesty, playfulness and willingness to serve the community in our local First Nation lore and around the world — something Rene did his whole life.

HAIDA GWAII: ISLANDS OF MIST

Steeped in mist and mythology, the islands of the Queen Charlottes abound in local lore that surrounds their beginnings.

Today, the Hecate Strait is a tempestuous 40-mile wide channel that separates the mist-shrouded archipelago of Haida Gwaii from the BC mainland. Haida oral tradition tells of a time when the strait was mostly dry, dotted here and there with lakes. During the last ice age, glaciers locked up so much water that the sea level was hundreds of feet lower than it is today. Soil samples from the sea floor contain wood, pollen, and other terrestrial plant materials that tell of a tundra-like environment.

The court is still out on whether or not the strait was ever completely dry during these times, but it certainly contained a series of stepping-stone islands and bridges that remained free of ice.

An ancient Haida tale, recorded in the late 1800s by a Hudson’s Bay Company trader, records the island's glacial history. Scannah-gan-nuncus, a boy who lived in the village now called Skidegate, had canoed up the Hunnah, a once roaring tributary to Skidegate Channel that is now a rocky creek, seldom deep enough to navigate.

The Haida the legend accurately records that it used to be several times deeper. Tired from paddling upstream, Scannah-gan-nuncus landed to take a nap. “In those days at the place where he went ashore were large boulders in the bed of the stream, while on both sides of the river were many trees. While resting by the river, he heard a dreadful noise upstream. Looking to see what it was, he was surprised to behold all the stones in the river coming toward him. … all the trees were cracking and groaning … he went to see what was crushing the stones and breaking the trees. On reaching them, he found that a large body of ice was coming down, pushing everything before it.”

Scannah-gan-nuncus’ experience with the glacier would have been familiar to the inhabitants of the Queen Charlottes. In recent years, the highest peaks are often bare of vegetation and snow-covered during most of the year, but back in the time of the glaciers, these same local mountains were the birthplace of advancing ice.

Precipitation and a significant drop in temperature gave rise to the Queen Charlottes ice-sheet, a thick mass of flowing ice that ran tandem with the Cordilleran sheet in the Hecate Lowlands.

Strolling around you can see where the glaciers left their mark on the Islands’ U-shape valleys, once a steep V-shape, now scoured smooth by glaciers that also deposited the erratic boulders can been seen sitting like sentinels on the beach.

CRETACEOUS NANAIMO GROUP

The strata near Nanaimo and much of eastern Vancouver Island is underlain by sedimentary rocks of the Cretaceous Nanaimo Group. These mudstones, sandstones and conglomerates were deposited in deltas, rivers and marine environments between 95 and 65 million years ago. While there is a mix, almost all of the great fossil exposures are marine.

CAMBRIAN TRILOBITES

The Cambrian was a time of expansion for the Earth's complex animal forms. Molluscs and arthropods and their friends with hard shells and exoskeletons dominated the seas. The specimen you see here is of a Wanneria dunnae trilobite from the Eager Formation, Rifle Range site near Cranbrook, British Columbia.

GOD JUL // MERRY CHRISTMAS

PLAYFUL SEALS: MIGWAT

Seals—those sleek, playful creatures that glide through our oceans and lounge on rocky shores—are part of a remarkable evolutionary story stretching back millions of years. 

Though we often see them today basking on beaches or popping their heads above the waves, their journey through the fossil record reveals a dramatic tale of land-to-sea adaptation and ancient global wanderings.

Seals belong to a group of marine mammals called pinnipeds, which also includes sea lions and walruses. 

All pinnipeds share a common ancestry with terrestrial carnivores, and their closest living relatives today are bears and mustelids (like otters and weasels). 

While it may seem unlikely, their ancestors walked on land before evolving to thrive in marine environments. It takes many adaptations for life at sea and these lovelies have adapted well. 

The fossil record suggests that pinnipeds first emerged during the Oligocene, around 33 to 23 million years ago. 

These early proto-seals likely lived along coastal environments, where they gradually adapted to life in the water. Over time, their limbs transformed into flippers, their bodies streamlined, and their reliance on the sea for food and movement became complete.

In Kwak'wala, the language of the Kwakwaka'wakw First Nations of the Pacific Northwest, seals are known as migwat, and fur seals are referred to as xa'wa.

JELLYFISH: DANCERS OF THE DEEP

This lovely ocean dancer with her long delicate tentacles or lappets and thicker rouched oral arms is a jellyfish. 

Her brethren are playing in the waters of the deep all over the world, from surface waters to our deepest seas — and they are old. They are some of the oldest animals in the fossil record.

Jellyfish and sea jellies are the informal common names given to the medusa-phase or adult phase of certain gelatinous members of the subphylum Medusozoa, a major part of the phylum Cnidaria — more closely related to anemones and corals.

Jellyfish are not fish at all. They evolved millions of years before true fish. The oldest conulariid scyphozoans appeared between 635 and 577 million years ago in the Neoproterozoic of the Lantian Formation, a 150-meter-thick sequence of rocks deposited in southern China. 

Others are found in the youngest Ediacaran rocks of the Tamengo Formation of Brazil, c. 505 mya, through to the Triassic. Cubozoans and hydrozoans appeared in the Cambrian of the Marjum Formation in Utah, USA, c. 540 million years ago.

I have seen all sorts of their brethren growing up on the west coast of Canada. I have seen them in tide pools, washed up on the beach and swam amongst thousands of Moon Jellyfish while scuba diving in the Salish Sea. Their movement in the water is marvellous.  

In the Kwak̓wala language of the Kwakiutl or Kwakwaka'wakw, speakers of Kwak'wala, of the Pacific Northwest, jellyfish are known as ǥaǥisama.

The watercolour ǥaǥisama you see here in dreamy pink and white is but one colour variation. They come in blue, purple, orange, yellow and clear — and are often luminescent. They produce light by the oxidation of a substrate molecule, luciferin, in a reaction catalyzed by a protein, luciferase.