What’s real, what’s borrowed, what’s simplified

Spinyhead is built on field research, but it’s still a game. A real coral head doesn’t pack this much action into one afternoon, and not everything the fish do here has been recorded for these exact species. This page sorts that out.

Every behavior on the reef falls into one of four groups. The references are in the About section of the game’s menu.

• DocumentedRecorded in published studies of these Caribbean species, or in my own field observations, marked as such.
• BorrowedDocumented, but in another ocean, another species, or in captivity, and applied to this reef.
• ExtrapolatedPlausible from how these animals live, but not recorded as shown. My judgment calls.
• SimplifiedReal behavior, with time, frequency or crowding compressed so you can see it in one game.

Documented for these species

• Fights for holes, evictions

  Spinyheads compete for shelter holes, bigger fish win, and bigger fish sit higher where the current brings more food (Buchheim & Hixon 1992; Clarke & Tyler 2003).

• Courtship, spawning, guarding

  Females lay in the male’s hole and he guards the eggs alone (Clarke & Tyler 2003). Egg fanning and male care are general to tube blennies.

• Bluehead wrasses catching blennies, the gape display

  From my own field observations of spinyheads on St. Thomas reefs, not from a published study. Bluehead wrasses are mostly plankton and small-invertebrate feeders, but I watched them take blennies caught out of their holes. I also watched residents gape and shake their heads at rival blennies, while simply dropping into the hole when a predator came near.

• Copepod escapes, feeding in a swell

  Calanoid copepods detect a striking blenny and jump clear, and water motion changes capture success (Clarke, Buskey & Marsden 2005; Waggett & Buskey 2007; Finelli et al. 2009).

• Cleaning gobies: regular customers, nests, new partners, single females, small intruders, threats, chases, mate guarding, ignored intruders

  Pairing, station defense and responses to intruders by sex and size (Harding et al. 2003; Harding 1993).

• Cleaning stations: the approach, color change, into the jaws, all done

  Caribbean clients pose for cleaner gobies and signal when they are finished (Côté, Arnal & Reynolds 1998; Côté 2000). The specific color changes shown for each predator haven’t been measured species by species.

• Foureye butterflyfish: the eyespot, juveniles, individual eyespots, the isopod rider

  Eyespot size, shape and variation, and the infection rate and weight of Anilocra (Meadows 1993; Meadows & Meadows 2003). The functions of the eyespot are hypotheses, argued from measurements, not tested with predators.

• Trumpetfish riding other fish, hiding in sea rods

  Trumpetfish shadow larger fish to approach prey, and pick escorts of similar color (Aronson 1983; Matchette et al. 2023, 2025).

• Grunt migrations, wrasse spawning sites, egg thieves, triggerfish eating urchins, the water jet, night-grazing urchins

  Ogden & Ehrlich 1977; Warner 1988; Robertson & Hoffman 1977; Randall 1967; Lessios 1988.

• Copepod swarms, the swarm breaking up, larvae drifting off

  Reef copepods swarm near coral by day and scatter at dusk (Hamner & Carleton 1979). Reef fish larvae spend weeks in the plankton, and few return to settle.

• Octopus camouflage, the frogfish’s strike

  Hanlon & Messenger 1996; Pietsch & Grobecker 1987; Grobecker & Pietsch 1979.

Borrowed from other reefs or species

• A wall of mouths

  Planktivores stripping food from water crossing a reef was measured on the Great Barrier Reef (Hamner et al. 1988), not in the Caribbean.

• Twilight hunt

  The dusk and dawn predation peak was described for Hawaiian reef fishes (Hobson 1972).

• Following a hunting moray

  The best-documented case is a giant moray and a roving grouper hunting together by day in the Red Sea (Bshary et al. 2006). Caribbean morays hunting at night, followed by graysbys, snappers and trumpetfish, is my application of it.

• Fish following a hunting octopus

  Documented mostly at an oceanic archipelago off Brazil and other Atlantic sites (Sazima et al. 2007; Krajewski et al. 2009; Mather 1992). A blenny being flushed from a loose hole is extrapolated.

• Eating in a bell, feeling into holes

  The cannibalism and bell-shaped hold come from a study I co-authored on Octopus vulgaris (Hernández-Urcera et al. 2019). Caribbean reef octopuses may be a different species in that group. That the suckers can’t grip octopus skin is described as likely, not proven.

• Predators calmer while being cleaned

  Shown for an Indo-Pacific cleaner wrasse and its predatory clients (Cheney, Bshary & Grutter 2008), applied here to Caribbean cleaner gobies.

• Goby clutch size and hatching

  Clutch size, egg size and incubation time come mostly from aquarium breeding (Olivotto et al. 2005), and wild values may differ.

Extrapolated

Each of these fits what’s known about the animals involved, but I’m not aware of a record of it happening as the game shows.

• A new owner eats the eggs

  Egg eating by guarding males is well known in fishes (filial cannibalism), but a male taking over a hole and eating the previous owner’s eggs hasn’t been documented for spinyheads.

• Urchin scraps on the current, the free-for-all

  Triggerfish tear open urchins and scavengers crowd in, but blennies taking drifting roe, and wrasses being too busy to hunt blennies, are extrapolated.

• Blennies eating newborn seahorses

  Not recorded. A newborn longsnout seahorse may be near the largest prey a spinyhead can swallow.

• Trumpetfish behind a coney

  Trumpetfish usually shadow herbivores like parrotfish. A coney flushing a blenny into a trumpetfish’s path is a game scenario. So is the trumpetfish switching to a silvery, blue-snouted phase to hunt chromis.

• Distracted diners, the snapper’s run

  Predation at spawning sites is documented for wrasses (Robertson & Hoffman 1977). Which predators come, and how often they target distracted fish, are the game’s choices.

• A moray at the station

  Morays are cleaned on many reefs, but regular visits to sharknose goby stations are less well documented than for other clients.

• An urchin grazing over a worm

  A plausible hazard for a slow-moving grazer and a shadow-triggered worm, not a measured event.

• The goby pair’s greeting, infected foureyes sheltering

  Both behaviors were observed, but their meanings (mate recognition; helping the isopod’s young find hosts) are hypotheses.

• Grunt droppings and new worms

  Resting grunt schools fertilize the corals they shelter over (Meyer et al. 1983). That this makes Christmas tree worms settle sooner, and so creates more blenny holes, is my extrapolation.

Simplified for the game

• Coral spawning

  Caribbean corals spawn once a year, a few nights after a late-summer full moon. Here they spawn after every full moon.

• Seahorse pregnancy

  A brood takes under three days in the game and about two weeks in the wild.

• Storm swells

  A swell rolls in every few days, far more often than real storms.

• A crowded coral head

  One coral head holds a cleaning station, a chromis cloud, a grunt school, sea rods with seahorses and a trumpetfish, an octopus, morays, a frogfish and passing sharks. Each is real, but you would rarely see all of them around one coral head in a single day.

• A full triggerfish

  How long a triggerfish stops hunting after a meal hasn’t been measured. The game picks a time.

• Energy, growth and eggs

  How much food a strike is worth, how fast a blenny grows, and how many eggs it can afford are game numbers, tuned to match the patterns in the studies, not measured values.

General natural history, specific study not yet attached

These are standard reef natural history, found in field guides and textbooks, but I haven’t yet linked each to a specific study: the graysby’s suction strike, the triggerfish’s locking spine, urchins pointing spines at shadows, morays hunting at night, wrasses sleeping in the sand, fish clearing out when a shark passes, butterflyfish nipping worm plumes, butterflyfish being cleaned and trumpetfish striking from the sea rods.

Spot something wrong, or know of a study that confirms or contradicts one of these? I’d like to hear it. A field observation that fills one of these gaps is exactly what this page is for. — Jason Buchheim