The Crown-of-Thorns Starfish

Clouds of reef fish and corals at Papahānaumokuākea Marine National Monument.

I know I just did a post on National Donut Day, but that piece was both tongue-and-cheek and nakedly self-interested.  Clearly donuts are ephemera with transient importance—scraps of fried dough which stay tasty for less time than flowers bloom (indeed I enjoy juxtaposing their cheap impermanence with the vast seemingly eternal universe in my paintings).  Today I looked at my calendar to find that June 8^th is World Oceans Day!  Unlike National Donut Day (which is self-evidently a meretricious marketing “holiday”), World Oceans Day strikes me as an important and worthwhile day of observance.  The ancients celebrated the oceans with festivals and sacrifices to venerate the sea gods.  We tend to regard the oceans as an inexhaustible source of cheap fish and a place to dump our rubbish.  I worry that the careless industrialized spoiliation of the oceans is the gravest mistake humankind is currently making (and we have our grubby grasping fingers in lots and lots of pies—and are making plenty of errors).  Yet, I don’t want this blog to become an angry jeremiad or an environmentalist harangue.  I want to celebrate the beauty and grace of the oceans and their inhabitants while also underlining the stress and danger which these vast swaths of the world are facing.  What to do?

An infestation of Crown-of-Thorns Starfish

For World Ocean Day therefore I am writing about the lifeform which, to me, most exemplifies the oceans of the late Holocene/early Anthropocene, the crown-of-thorns starfish, Acanthaster planci. This echinoderm is a ravenous poisonous destroyer which is exploiting the sickness of the oceans to proliferate and succeed wildly (at the expense of everything else).  It is an amoral ravenous monster covered with toxic spines which is eating the coral seas bare.  It is also a beautiful creature magnificently evolved to thrive—we can hardly hold its horrifying success against it.  Maybe it should be on the cover of Forbes smoking a cigar and bloviating about its philosophy of success.  By chance the starfish also lies at an intersection of many blog topics—crowns, invaders, colors, poison, mollusks (for its fate is connected with that of predatory mollusks), opinion, and science…perhaps even “deities of the underworld”.  This is a lot of introduction…let’s meet our antihero!

Crown of Thorns (Acanthaster planci) photo by jon hanson

The crown-of-thorns starfish (or “sea star”), Acanthaster planci takes the form of a spiked disk with up to 21 prehensile arms (also covered in spines). On its underside, the starfish has numerous sticky tube-like suction feet running along the bottom of each arm. These legs run in parallel rows beside a series of closely fitting plates which form a central groove on the bottom of each arm.  The arm grooves each run ominously into the starfish’s horrifying stomach/mouth.  The starfish can grow to a diameter of up to 80 centimeters (31 inches) although they are more commonly found in the 35 centimeter range.  Acanthaster planci has a wide Indo Pacific range and lives in tropical and semitropical coastal waters from the Red Sea and the East Coast of Africa across both the Indian and Pacific Oceans all the way to the West Coast of Central America.  The starfish are usually dull grays and reds but they can range to brilliant purple, blue, orange, aqua (or display all sorts of mixed ranges). Their colors are highly mutable and variable! These starfish eat coral polyps!  It crawls into corals by means of its many sucker feet—compressing or elongating its body as needed.  When in position the starfish extrudes its stomach over the polyps it wishes to eat: the stomach can cover an area approximately equal to the starfish.  The creature then releases digestive compounds which dissolve the soft parts of the coral into a soup which the starfish slurps up.  It then retracts its stomach and moves on, leaving a bleached (i.e. dead) patch of coral skeleton.  A medium sized starfish can consume up to 6 square meters (65 sq ft) of living coral reef per year.  If times are lean the starfish can go for months (or longer) without eating. http://www.arkive.org/crown-of-thorns-starfish/acanthaster-planci/video-00.html Crown-of-thorns starfish are male or female and they do not reproduce by budding, but female starfish lay from 6.5 million to 14 million eggs each per breeding season [hereupon the author wiped his furrowed brow].  When the eggs hatch there are several interesting larval stages which the echinoderm goes through before reaching their adult form.  Suffice to say, the starfish reaches sexual maturity after 2 years and it lives as long as 8 years. Fourteen million offspring per season is a lot!  If predators do not keep the crow-of-thorns starfish in check, they can swiftly overrun entire reef systems and eat all the coral into bleached uninhabitable wasteland.  This leaves all of the multitudinous reef inhabitants homeless.  The reef skeletons dissolve in our newly acidified oceans and one of earth’s most diverse ecosystems becomes a weed-strewn graveyard. The starfish are hard to stop since they are provided with tremendous defenses: each animal is covered with 1-5 centimeter long razor sharp spines which in turn are covered with toxic saponins—soaplike chemicals which interact with cholesterols to tear holes in cell membranes.  The starfish can regenerate arms.  If removed from the water, the starfish develops holes in its body and loses its water, but it can swiftly reconstitute itself if placed back in the ocean.

Crown-of-thorns starfish wash up in Japan (BBC)

Fortunately there are some tough predators of the crown-of-thorns starfish.  Certain triggerfish, parrotfish, and blowfish can insouciantly crunch through the spines with hardened mouths.  Painted shrimp and polychaete worms can tear off and eat pieces of the starfish until the latter dies (whereupon the impatient scavengers devour the corpse).  Best of all, the magnificent Triton’s trumpet, a huge gastropod mollusk, can rasp the odious starfish to pieces with its sharpened radula and suck up the offending echinoderm!  Unfortunately, the fish are vanishing into the aquarium trade or the soup pot and the tritons have been killed en masse so their shells can be sold to tourists.  This results in a feedback loop wherein the crown-of-thorns devastate a reef to the extent that the predators can not survive at all.  The plague of starfish then descend of virgin reefs and kill them off too.

A plague of crown-of-thorns starfish (Photo: AFP/Getty Images)

Healthy reefs have a certain ability to fight off the crown-of-thorns star, but today’s reefs are coping with overfishing, invasive creatures, acidification, pollution, and fluctuating temperatures.  The crow-of-thorns is exploting these weaknesses (and the diminished stock of its predators) to run rampant.  Humans have stepped in late to try to kill of the rampaging multi-armed villains, but, for all of our skill at doing in other organisms, we seem to not be very good at killing these fiendish starfish.  They are difficult to rip apart.  They are hard to net or trap.  They are surprisingly resistant to punctures.  Recently divers have had success suppressing infestations by injecting the starfish all individually with sodium bisulphate (which echinoderms and my great uncle cannot abide, but which is relatively harmless to most other lifeforms).   Obviously this is an expensive and labor intensive solution (although if somebody wanted to hire me as a starfish bounty killer, I would not decline).

New frontiers of pest control (via DIVE QUEENSLAND)

The common name of the crown-of-thorns starfish is a reference to Christian mythology.  One of the tortures endured by Jesus was a crown woven of thorns (which pierced his temple and hurt him while simultaneously mocking his alleged crime—pretending to the throne of Judaea).  Throughout Christian art, the crown of thorns is the supreme crown of the king of kings which he wears during the passion or as he harrows the underworld.  The voracious starfish earned its sobriquet not by godliness, but by looking like a horrible alien crown made of thorns (and arguably also by bringing death and devastation to coral reefs).  I find it to be one of the most poetic and horrifying common names in all of taxonomy—and as the starfish destroys ecosystem after ecosystem, it seems fully earned.

A giant triton snail feeding on crown-of-thorns starfish. Image supplied by Australian Institute of Marine Science

The Prickly Pear

Blind-Eye Prickly Pear

Opuntia is a genus of cactus which produces a sweet studded fruit–the prickly pear. Like all true cacti, the Opuntia genus comes from the Americas. Opuntia plants are naturally occurring from Connecticut and Long Island west to Chicago and southern Canada! More and more species can be found growing in the American southwest down into Mexico (where the greatest diversity of Opuntia species are found). Varieties of the plants also grow naturally throughout Central America, the Caribbean, and down into South America (although “naturally” might be the wrong word—the peoples of the Americas have been instrumental in the spread of these plants for a long time).

A prickly pear (Opuntia) clonal colony in fruit

Opuntia plants consist of large flat green pads which have two sorts of spine. There are long sharp hard spines capable of drawing blood & causing serious injury, but also, more insidiously, there are infinitesimal hairlike prickles called glochids. If touched, these glochids feel like fur but the microscopic ends break off and penetrate the skin where they prickle agonizingly. Argh! Just writing about them is making me itch.

Prickly pears are incredibly hardy plants which are resistant to drought, disease, and animals. They easily grow into great clonal colonies which people sometimes use as a sort of natural fence. In the sixties, Cuba planted a prickly pear wall all around the American military base at Guantanamo Bay so that fleeing dissidents would be unable to seek shelter there.

An opuntia hedge towers over travelers on camelback

However it is not for its spines, its toughness, or its prodigious ability to grow that the prickly pear is principally known, but for its sweet colorful fruit. These cactus fruits are colloquially (but wrongly) known as “pears” or “figs” in English (and endless other names in many, many other languages). The fruit are filled with delicious juice, tasty flesh, and hard but edible seeds. The fruits have only modest amounts of essential nutrients (particularly fiber, vitamin C, and magnesium), but they are filled with phytochemicals–a catch-all term for molecules made by plants which may have biological/medical significance. Scientists believe prickly pear fruit may be beneficial for mitigating the negative health consequences of diabetes, high cholesterol, and obesity (and hangovers too). Additionally, certain prickly pear phytochemicals may have antiviral and anti-inflammatory properties. There were lots of ambiguous words and conditional phrases in there. I don’t know what to tell you…Medical science is working on it, but they have a lot on their plate.

Whatever the health benefits, prickly pear is delicious and it grows in places where other things do not. This means the plant has been imported to Australia, Asia, Africa, the middle east, and many other places. It is easy to grow, and hard to kill, so prickly pear is (quietly) one of the great invasive species of the time. Since it has mostly established itself in forsaken deserts where nothing was growing anyway, nobody is particularly worried…for the moment. Did I mention forsaken deserts? The prickly pear is particularly at home in Israel and Palestine where it has become an integral part of both cultures. I was first shown how to cut open and eat prickly pears by a Jew who said that hardened native-born Israeli Jews who farm the desert call themselves “sabras” (the modern Hebrew term for the fruits) because they are spiny and tough on the outside but sweet and generous in their hearts.

I really like prickly pears and I have been wanting to make a bunch of prickly pear ice cream custard. I will let you know how this project goes…I have the feeling it is going to turn into a big hilarious magenta mess, so stay tuned for that!

The Lowland Streaked Tenrec

Lowland Streaked Tenrec (Hemicentetes semispinosus)

Despite appearances, this spiky creature was not lovingly crafted by Hieronymus Bosch. Instead it is a real animal–a lowland streaked tenrec (Hemicentetes semispinosus) which is a native of the wandering micro-continent of Madagascar (presently located off the east coast of Africa).   The little tenrec weighs only 200 grams (7 ounces) and measures 13-17 cm (5-6.5 inches) from the tip of its pointy bewhiskered snout to the end of its vestigial tail. The yellow-and-black creature is covered with scattered quills (some of which it can detach at will). The little animal lives in the eastern coastal rainforest where it subsists primarily on worms and small arthropods. It is active both by night and day.

But perhaps you are asking just what a tenrec is to begin with (my word processor, for example, obdurately refuses to recognize the word). The tenrecs are a group of omnivorous (though largely insectivorous) mammals which live throughout Madagascar and sub-Saharan Africa. They seem to be descended from some basal line of edentate mammals—as evidenced by their low body temperature and by the fact that they have a cloaca (a multi-purpose orifice for excretion and reproduction). Across their range tenrecs evolved to fill many different ecological niches. Thanks to convergent evolution, various species of tenrecs look like mammals more familiar to us such as otters, opossums, rats, and shrews (the lowland streaked tenrec, for example, appears analogous with the insectivorous hedgehog) but these appearances are superficial. Tenrecs seem to be distantly related to other African mammals like elephant shrews, sirenians, and hyraxes. Their only close relatives seem to be the extraordinary golden moles (like Grant’s golden mole, the exquisite sand swimmer of the Namib Desert).

As you might expect the lowland streaked tenrec utilizes its quills to deter predators—namely the disquieting fossa and various other carnivorous Malagasy mongooses. The tenrec can pivot the barbed spikes on its back and neck into an upright crest. Thus armed, the colorful little animal charges boldly at predators–which must perforce retreat or contend with a face full of barbed spikes. The lowland streaked tenrec is also unique among mammals in that it uses its spines for stridulation—a violin-style method of producing sounds to communicate. Like a cricket, the lowland streaked tenrec vibrates its quills together to make a strange shivering chatter (useful for finding mates and communicating in groups). You can hear the strange noise in the peculiar Youtube video below.

Female tenrecs mature quickly and can reproduce in as few as 25 days after they are born. They give birth to litters of 3 to 7 young.

The Gafftopsail Catfish

Gafftopsail Catfish (Bagre marinus)

This amazing looking fish is a gafftopsail catfish (Bagre marinus). It is an Atlantic Ocean catfish which lives in coastal waters off of North America from the Caribbean up through the Gulf of Mexico north to the mouth of the Hudson. As you might guess from its intimidating Fu Manchu mustache and barbed flavor savor, the gafftopsail catfish is a formidable predator which eats crustaceans and smaller fish. The fish has a sinister forked tail, a wavelike hump, and a jaunty dorsal spine looks like a sail (and gives the fish its common name). Additionally like most saltwater catfish, the gafftopsail catfish has several venomous, serrated spines.

The largest gafftopsail catfish ever caught weighed an impressive 4.5 kg (10 pounds), but generally the fish are much smaller. They usually measure about 43 cm (17 inches) in length. Male gafftopsail catfish are solicitous fathers. When the female lays her eggs, the male fertilizes them and collects them in his mouth. He carefully protects the eggs until they have hatched, and thereafter his young take shelter from predators inside his mouth until they are old enough to set out on their own.

Turkeyfish

Zebra Turkeyfish (Dendrochirus zebra)

At present, I am in no danger of coming into ownership of a yacht, but if I had one I kow what I would name it–the “Turkeyfish” a magnificent combination of my favorite bird and a lovely fish.  But “turkeyfish” is not just a funny portmanteau or an impossible chimera, there are actual turkeyfish swimming the world’s waters.

Dendrochirus is a genus of small scorpionfish which live in the Indo-Pacific region: these dwarf lionfish are also known colloquially as turkeyfish. They are members of the Pteroinae subfamily of the Scorpionfish family (a family which includes some of the world’s most poisonous fish) and, like their relatives they have fans of sharp spines coated with venomous mucus.  Because these spines are striped and shaped like the feathers of turkeys, divers fancifully call them turkeyfish (a common name which is sometimes even extended to larger lionfish of the Pterois genus).

Shortfin turkeyfish or Dwarf Lionfish (Dendrochirus brachypterus)

Turkeyfish are formidable carnivores (for their size) with large powerful mouths and the ability to lurk in shadows and stalk prey around a reef.  They mostly prey on small fish, arthropods, and mollusks but occasionally they eat big fish—or each other. The poisonous spines of turkeyfish cause large predatory fish to avoid them and their toxin is also venomous to animals other than fish (like humans which can be badly hurt, or even occasionally killed by the spines). The exquisite colors of these spines serve as a warning to predators, but have also caused the fishes to be popular in the aquarium trade.

Zebra Turkeyfish (Dendrochirus zebra)

Some species of lionfish have even been spreading around the tropical waters of the globe after irresponsible aquarists freed them into the ocean.  It is unclear whether the turkeyfish have joined their larger cousins in invading non-native reefs but it is clear they are formidable fish.

Brown Bullheads

[As a special weekend treat–and in keeping with this week’s theme, kindly find a repeat of a post about brown bullhead catfish from 3 years ago]

The most common catfish in New York State is the brown bullhead catfish (Ameiurus nebulosus) a fish sometimes also gracelessly known as the “mud pout” or the “horned pout”.  The brown bullhead lacks the beauty and charisma of many other catfish.  It is not electrical, has no armor, does not walk, and does not grow to immense size (average fish are usually 14 inches long or smaller).   It has two-tone coloration: unremarkable brown above and off-white below (although, like most fish, it can adapt somewhat to local conditions).

 

The Brown Bullhead Catfish

The fish does however illustrate one of the reasons I like catfish and write about them so much.  It is the most common catfish of New York State, a state marked by extreme differences of population density, landscape, temperature, and water quality. The brown bullhead is a hard-to-kill generalist which does well everywhere in the state (and throughout the east coast, the Great Lakes, the midwest, and the south).  It can be found in Prospect Park, a short walk from my apartment just as easily as in a cold Adirondack lake. The New York State Department of Environmental Conservation website describes the fish as follows:

Brown bullheads are probably the most adaptable member of the catfish family and live in a wide variety of habitats. They exemplify the hardiness of catfishes in general, tolerating both high water temperatures and low oxygen levels. They are present in many cool Adirondack lakes and often abundant in warm water ponds, lakes, and larger, slow moving streams. They occur in areas with or without aquatic vegetation and can be found over both muddy and gravelly bottoms.

The brown bullhead has the same exquisitely refined senses as other catfish.  Its whole body is covered with taste buds, which are particularly numerous on its eight barbels.  Though not especially large, the creature is strong, agile, and flexible.  An omnivore, the brown bullhead is protected from predators by the extremely sharp spines on its dorsal fin and its pectoral fins.  Both parents builds nests together and together they protect the eggs and even the young fry for a while after hatching.  Most astonishingly, the fish is heartily indifference to water pollution which makes it the foremost city catfish.  Below it is pictured with the other common New York City fish.  It is apparently a reasonably fun sportfish, although some fishing experts think that it is only suitable for child anglers (due to how extensively it can be found).   When not caught in polluted water it makes a tasty meal.

Whereas I usually write about invasive species coming from some exotic locale to the United States, the brown bullhead is the opposite.  When introduced abroad it has been the classic ugly American, stealing food and habitat from native species or eating them outright (which seems even more gauche than my habit of anxiously overtipping). Large populations have now established themselves in Europe, Russia, China, Australia, and New Zealand and the fish keep expanding their range.

“Free me petty human! Soon your world will belong to us!”

The Brown Bullhead Catfish

The most common catfish in New York State is the brown bullhead catfish (Ameiurus nebulosus) a fish sometimes also gracelessly known as the “mud pout” or the “horned pout”.  The brown bullhead lacks the beauty and charisma of many other catfish.  It is not electrical, has no armor, does not walk, and does not grow to immense size (average fish are usually 14 inches long or smaller).   It has two-tone coloration: unremarkable brown above and off-white below (although, like most fish, it can adapt somewhat to local conditions). 

The Brown Bullhead Catfish

The fish does however illustrate one of the reasons I like catfish and write about them so much.  It is the most common catfish of New York State, a state marked by extreme differences of population density, landscape, temperature, and water quality. The brown bullhead is a hard-to-kill generalist which does well everywhere in the state (and throughout the east coast, the Great Lakes, the midwest, and the south).  It can be found in Prospect Park, a short walk from my apartment just as easily as in a cold Adirondack lake. The New York State Department of Environmental Conservation website describes the fish as follows: 

Brown bullheads are probably the most adaptable member of the catfish family and live in a wide variety of habitats. They exemplify the hardiness of catfishes in general, tolerating both high water temperatures and low oxygen levels. They are present in many cool Adirondack lakes and often abundant in warm water ponds, lakes, and larger, slow moving streams. They occur in areas with or without aquatic vegetation and can be found over both muddy and gravelly bottoms.

The brown bullhead has the same exquisitely refined senses as other catfish.  Its whole body is covered with taste buds, which are particularly numerous on its eight barbels.  Though not especially large, the creature is strong, agile, and flexible.  An omnivore, the brown bullhead is protected from predators by the extremely sharp spines on its dorsal fin and its pectoral fins.  Both parents builds nests together and together they protect the eggs and even the young fry for a while after hatching.  Most astonishingly, the fish is heartily indifference to water pollution which makes it the foremost city catfish.  Below it is pictured with the other common New York City fish.  It is apparently a reasonably fun sportfish, although some fishing experts think that it is only suitable for child anglers (due to how extensively it can be found).   When not caught in polluted water it makes a tasty meal.

Whereas I usually write about invasive species coming from some exotic locale to the United States, the brown bullhead is the opposite.  When introduced abroad it has been the classic ugly American, stealing food and habitat from native species or eating them outright (which seems even more gauche than my habit of anxiously overtipping). Large populations have now established themselves in Europe, Russia, China, Australia, and New Zealand and the fish keep expanding their range.

"Free me petty human! Soon your world will belong to us!"