40 Fun Facts About Diatoms

Diatoms generate an estimated 20 to 50 percent of which gas produced on Earth each year?

Oxygen is a by-product of their photosynthesis, and diatoms also make up nearly half of the organic material found in the oceans.

A 1961 incident in Capitola, later linked to a diatom toxin, helped inspire which Hitchcock film?

The Birds drew on the night disoriented seabirds slammed into Capitola homes. Toxic algae were later blamed, though nobody knew that in the 1960s.

Alfred Nobel soaked unstable nitroglycerin into diatomaceous earth to create which safer explosive?

Dynamite was patented in 1867 after Nobel found the porous powder made nitroglycerin stable enough to transport and handle.

Dust from ancient diatom shells crosses the Atlantic to fertilize the Amazon from which desert?

Sahara dust reaching the Amazon comes in large part from the Bodélé Depression in Chad, an ancient lake bed whose diatom-rich sediment carries phosphorus the rainforest needs.

Forensic scientists test a body's tissues for diatoms to help confirm which cause of death?

Drowning is suggested when diatoms matching the local water turn up inside a body, because their hard shells do not readily decay and never occur there naturally.

Diatoms pull which glassy compound out of the water to build their intricately patterned cell walls?

Silica in a hydrated form makes up the two-part shell, and diatoms take in over 6.7 billion tonnes of silicon from the water every year to build it.

The invasive river diatom Didymosphenia geminata forms slimy mats known by which blunt nickname?

Rock snot, also called didymo, is native to the Northern Hemisphere but became an invader in New Zealand, where it had never been found before.

Diatomite has long served as a mild abrasive in metal polishes and which bathroom product?

Toothpaste, metal polishes and some facial scrubs have all used the crumbly powder, which is made of fossil diatom shells built up over millions of years.

Whalers nicknamed which giant 'sulphur bottom' after the yellowish diatom film on its belly?

Blue whale bellies can carry a coating of huge numbers of diatoms, which tinges some individuals yellow. Herman Melville mentions the nickname in Moby-Dick.

Diatom shells are made of the same mineral as which gemstone, earning them a 'living' nickname?

Opal is the hard mineral of the shell, and its shimmering structural color is why diatoms are called living opals and jewels of the sea.

Makers of wine and which other popular drink filter it through diatomaceous earth?

Beer and wine are both clarified this way, and the powder can also filter syrups and honey without altering their color, taste or nutritional properties.

Diatomaceous earth kills bed bugs and other insects mainly by causing which fatal effect?

Dehydration follows because the fine powder soaks up oily lipids from the waxy outer layer of the insect's exoskeleton, the barrier that normally holds water in.

Diatoms and cyanobacteria are among the most important groups in which drifting, sunlit community?

Phytoplankton in nutrient-rich coastal waters are often dominated by diatoms, because diatoms can divide more rapidly than the other groups.

Open-ocean diatom blooms, later ended by a nutrient shortage, typically peak at which time of year?

Spring brings the main bloom. A smaller, shorter-lived autumn bloom can follow when the summer layering of the water breaks down and stirs nutrients back up.

The slippery film of diatoms coating submerged river stones typically shows which color?

Brown coatings on stones and sticks are frequently diatoms, and the color comes from the yellowish chloroplasts where they photosynthesize.

Which naturalist found diatom remains in dust at Cape Verde and later puzzled over their beauty?

Charles Darwin called the tiny cases among the most beautiful of objects, doubted they were made for humans to admire, and put their beauty down to symmetry of growth.

The name diatom traces back, by way of Neo-Latin diatoma, to a Greek word with which meaning?

Cut in half suits the shell, which is built from two overlapping sections. The Greek word was diatomos, from a verb meaning to cut through.

Neither plants nor animals, diatoms belong to which catch-all group of mostly single-celled life?

Protists such as diatoms are eukaryotes, with a nucleus wrapped in its own envelope, which separates them from bacteria and archaea.

Diatoms help drive the ocean's biological pump, which locks which element away in the deep sea?

Carbon fixed by diatoms comes to 10 to 20 gigatonnes a year, and the small share that reaches the deep ocean stays out of the atmosphere for thousands of years.

Diatoms belong to the heterokonts, making the tiny cells surprising relatives of which seaweed?

Kelp and golden algae share the group with diatoms, as do water moulds, and many of its members have plastids rich in chlorophylls a and c.

Centric diatoms, one of the two main shape groups, are built with which kind of symmetry?

Radial symmetry gives centric diatoms their typically circular outline, but they are the minority: most diatoms belong to the other, elongated group.

Many open-water diatoms grow spines or link into long chains mainly to slow down which process?

Sinking is a constant risk because the dense shell drags cells down out of the sunlit surface, so spines and chains add drag that keeps them up longer.

Diatoms of the family Rhopalodiaceae carry a bacterial partner that lets them fix which gas?

Nitrogen fixing is the job of the spheroid body, a former cyanobacterium that has lost its ability to photosynthesize but still feeds its diatom host.

The world's largest deposit of diatomite is worked near the town of Lompoc in which US state?

California holds the deposit in Santa Barbara County, part of the Sisquoc Formation, while Nevada and Colorado have beds several hundred meters thick in places.

Which London scientific body published the first known drawings of diatoms in its Transactions?

Royal Society readers saw drawings of Tabellaria in 1703, sent by an unnamed English gentleman who had wondered whether the chains of tiny parallelograms were salt crystals or a plant.

Seafloor mud made of diatom shells builds up fastest in the deep waters of which ocean?

Southern waters hold a continuous belt of the mud that stretches around the globe, and the tiny shells that build it can take 20 to 50 years to settle to the seabed.

The earliest known diatom fossils, including one in amber from Thailand, date from which period?

Jurassic fossils are the oldest found so far, though molecular clocks hint that diatoms arose earlier, perhaps after the end-Permian mass extinction opened up marine niches.

Until World War I, nearly all diatomaceous earth came from Lüneburg Heath in which country?

Germany owes the find to a peasant, Peter Kasten, who struck the powder while digging a well in the 1830s. Extraction on the heath went on until 1994.

Berkefeld filters made of diatomaceous earth proved their worth in an 1892 Hamburg epidemic of what?

Cholera struck Hamburg in 1892, and the tubular filter candles developed by the Celle engineer Wilhelm Berkefeld were used successfully during the outbreak.

Diatom research belongs to which branch of biology, which also covers seaweeds and pond scum?

Phycology is the study of algae, and its specialists use the pores, ribs and spines patterned into each shell to tell diatom genera and species apart.

Which term names a diatom's hard, porous shell, built of two overlapping sections and girdle bands?

Frustule pores, called areolae, give the cell inside access to the outside world for jobs such as waste removal.

Geologists use which term for deep-sea mud rich in microscopic skeletons such as diatom shells?

Ooze is defined as sediment containing at least 30 percent skeletal remains of open-water microorganisms, and the diatom-rich kind lies on the deep ocean floor.

Most diatom species belong to which elongated group, the counterpart of the centric diatoms?

Pennate diatoms were split into two separate classes in a 1990 overhaul of diatom classification, while the centric forms stayed together as one.

Diatom chloroplasts appear to descend not straight from bacteria but from which group of algae?

Red algae are the likely donors, unlike in plants, whose chloroplasts came straight from bacteria. Diatom chloroplasts are wrapped in four membranes.

Which neurotoxin made by Pseudo-nitzschia diatoms causes amnesic shellfish poisoning in people?

Domoic acid upended the belief that only dinoflagellates made harmful algal toxins, after a deadly 1987 diatom bloom caused an outbreak of the illness.

Diatoms surprised biologists by having which metabolic pathway, once thought to begin with animals?

Urea cycle steps appear to help diatoms swap nutrients between the mitochondria and the rest of the cell, a different purpose from the waste disposal it handles in animals.

Some elongated diatoms glide over surfaces on mucilage secreted through which seamlike shell slit?

Raphe gliding only works on a solid surface the mucilage can grip, and it fooled an early naturalist into thinking the first described diatom was an animal.

Diatom cells get smaller with each division until which special cell forms to restore full size?

Auxospore formation is needed because each daughter cell keeps one old shell piece and grows a smaller one inside it, so the average cell size keeps falling.

Which carotenoid pigment do diatom chloroplasts contain alongside chlorophylls a and c?

Fucoxanthin is the dominant carotenoid in diatoms, handling up to 60 percent of the energy passed to chlorophyll a, and diatoms hold up to four times more of it than seaweed.

Pesticides containing diatomaceous earth must be registered with which US federal agency?

EPA registration is required even though the powder is considered relatively low-risk, while the FDA separately approves it as a feed additive that prevents caking.