March 2000
Strange Behaviour
Nope, this is not an article about Friday night in West End. It is the first, in a series about fish, their relatives, and some of the strange things that happen just out of site, beneath the waves. Octopus are nocturnal, during the day they sleep in crevasses and holes along the reef, or on the bottom. They will usually disguise the entrance by dragging a rock, shell or piece of coral into the opening behind them so they can sleep undisturbed.
At night, they come out to hunt. Octopus are fast, clever and lethal, well to mollusk anyway. If threatened or attacked, octopus can change color to match whatever type of coral they are on. If provoked further they move quickly turn very dark then shoot out a harmless cloud of black ink. The octopus then turns a very light color and heads off in a new direction, leaving its provoker biting into nothing but a black cloud. Octopus entrap prey in an eight legged. suction cupped grip. The first bite with their parrot like beak introduces a paralysing venom and a digestive enzyme. Our Octopus then slurps up the insides of its victim and discards the shell. Strange behaviour indeed. If they tried to show an alien culture on Star Trek this weird, no one would believe them. Octopus can lay up to 150,000 eggs at a time, females frequently die of starvation protecting a nest.
There are several species of octopus in the Bay Islands. Their favourite dinner is Lobster or shrimp. Octopus are commonly seen on night dives, and can be found by snorkels on the shallow reefs late in the afternoon.
Next month: Lobsters, more than just an excuse to eat garlic butter
April 3,2001
Strange Behaviour
Nope, this is not an article about driving on Roatan. It is about the source, of the favourite meal of most tourists visiting the island.
I can almost hear all the northerners chanting it now, "where are the claws ?" . Caribbean lobsters do actually have tiny claws, but they use those long barbed whips for hunting, which for our spiny lobster consists mostly of gathering up dead stuff off the ocean floor.
On the East Coast of the US, the slang word for lobsters is "bugs". Insects are insects because they have six legs and an exoskeleton. Lobsters have ten legs and an exoskeleton, and "Cute as a bug" is an expression you will never hear said about lobsters, with their stalked eyes and feathered mouths. They belong to an underwater family called Crustaceans.
Because lobsters have an exoskeleton, in order to grow, they must first shed their shell. But why waist a perfectly good shell? Before molting, lobsters re-absorb and store the calcium from their existing shell. Molting takes several hours to several days. I know it only takes you a few minutes to get all the meat out, but you have different tools and different goals. During the "soft shell" period they are most vulnerable to attack, and spend all their time hiding beneath rock ledges.
Lobsters are found under coral ledges, and in holes along the reef. Look for thier long hunting whips poking out during the day. At night they roam about in search of food. If threatened, lobsters can swim using powerful strokes of there muscular tail. Since they only swim to get away from a threat, they swim backwards, keeping an eye on their antagonist. While this form of evolution works well in one sense, it leaves the poor critter bouncing off everything in the ocean when threatened. Good thing they have a exoskeleton!
Next month: Urchins, Pin cushions of the sea
June 14,2000
Strange Behaviour
Sea Urchins, those less than cuddly little walking pincushions on the ocean floor, belong to a family called echinodermata, which make them close cousins to Sea Stars, Sand Dollars and Sea Cucumbers. The shells of each can often be found on the beech and have a distinctive five sided symmetry, the characteristic star shape. Another similarity amongst this family is the ability to pump salt water through capillaries in order to move all those legs, arms and spines.
The most common Urchin we see here on Roatan is the Long-Spine Urchin which have whitish grey spines as juveniles, and long black spines in adult hood. Amongst rocks and hiding in crevasses during the day, you will also find Reef Urchins, smaller in size with fewer stubbier spines, and in shallow water, you may also come across Variegated Urchins that look more like prickly snowballs.
All urchins are nocturnal, so during the day you will find them huddled into holes and cracks. At night however, they come out to feed on algae. Whether you are swimming, snorkelling, or scuba diving, the only way to get stuck by an urchin is for you to come in contact with them. Urchins are incapable of jumping up and attacking people, making them just one more, in a long line of misunderstood sea critters.
During night dives, we frequently observe adult long spines, working their way around the reef with a school of small fish in amongst the spines. The fish are obviously taking advantage of the spines for protection, and also help out the urchins with their plumbing problem. Urchins have a small round mouth, on the bottom surrounded by feeding arms and legs, and they poop through their tops, leaving the little fish to feed and five rows of tiny arms to clean up. A perfect little symbiotic community at work, everyone wins.
Next month: The wild and crazy sex life of fish
August 1, 2000 Strange Behaviour
Being that we are mammals and a bit self centered, it is often difficult to accept new ideas about how to get things done. Take fish reproduction for example. Flounders engage in an entire day of showing off, then they just swim past each other. The eggs are dropped and fertilized with zero contact.
Talk about safe sex!
Barnacles on the other hand do need physical contact, but being stationary animals firmly rooted in one spot, contact could be a problem. The solution makes male barnacles renowned in the animal kingdom for having the largest penises per body size around. I guess you had better hope the barnacle next door is everything you expected, cause there isn't much shopping around.
Parrott fish like to swing both ways, they all start out as males, switch to females in adulthood, and then as the community needs require, some individuals become super males. We see the large "super males" on the reef every day.
Corals and sponges do something called broadcasting. Each coral head or sponge can be made up of thousands of individuals. Somehow through a coordinated effort the entire community dispatches eggs and fertilizer at once, to drift along in the current mixing as it goes.
Four eyed butterfly fish and angel fish tend to choose one partner for life, much like some mammal species.
Next month: Misunderstood predators
November 8, 2000
Strange Behaviour
Misunderstood predators
In 1869 Jules Verne started the world thinking about life under the sea, unfortunately the part the world remembered was the giant killer octopus. Then just as people were starting to get back into the water, along comes Stephen Spielberg with "JAWS".
Sharks for the most part are shy, curious, and opportunistic. Caribbean Reef Sharks only eat once every fourteen days, and are then looking for something to nibble on that won't swim away too fast or put up a fight. A distracted or injured fish in a school for example. Short of going swimming with a couple pounds of raw hamburger in your shorts pocket, your chances of seeing one of these incredible creatures is pretty remote.
Barracuda have also been vilified without justification, simply because they like to hang around snorkelers. It's actually not their fault. Barracuda belong to a group of predator fish often referred to as shadow hunters. They stalk prey by hiding against something else, and if that something else happens to be big and moving and likely to scare up some small fish, all the better. Next time one of our torpedo shaped friends starts following you around, stay and enjoy the show.
Both sharks and barracuda are grey shaded, dark on top, light underneath. From above the dark colour fades in to the dark below, while their light bellies hide them against the light surface, from watchful eyes below.
December 10, 2000
Strange Behaviour
Starting you're day with a scrub down by some friends could be interesting fun but I think I would draw the line at teeth cleaning, and I definitely don't want anything alive crawling around in my mouth or nibbling bits off my eyes!
Cleaning stations offer some of the most entertaining and memorable experiences I have had underwater. Most reef fish come in for cleaning a couple times a day. While diving or snorkelling, you can often spot cleaning stations by looking for the cleaners and waiting, or by watching for odd behaviour, such as a big grouper sitting in a sponge with his mouth gaping open. The behaviour is symbiotic, the fish get rid of parasites, and the cleaners get a free meal. Somehow a truce is formed in the ever-present predator prey relationship. I've watched big old barracuda hover motionless while gobies dart in and out of their mouth and gills. Of course nothing is that straight forward on the reef, and it seems that some fish get a regular cleaning just for fun.
The most common cleaners are Pederson and Banded shrimp, Gobies and Fairy Basslets. Many types of juveniles also get in on the action when they can. Pederson shrimp live with anemones and will happily perform a manicure for you if your buoyancy is good enough to hover over their homes. The banded shrimp can always be spotted, by looking for their long white antennas poking out from under a ledge. Gobies of all description hang around on brain coral, and will also clean a divers hand if you are patient and hover in a non-threatening manor. I have had hair pulled out of the back of my hand by these little guys but the interaction was well worth it.
If you still can't find a cleaning station, follow some Creole Wrasse around for a few minutes. These are the small purple fish with the dark foreheads that tend to run in pacts causing commotion all over the reef. They don't seen to be able to go more than a few feet without a wash, and can often be seen lined up waiting their turn, look closely into the middle of the pack and you will see one hovering head down with his jaw thrust open. All just good clean fun.
January 22, 2001
Strange Behaviour
Coral reef is one of the major attractions of the Bay Islands. One of the most commonly asked questions I get is "Is coral plant or animal?" Naturalist Jean Peyssonel was thrown out of the Academy of Sciences in the seventeen hundreds when he suggested it to be animal. We know today that coral is a round little animal with a mouth surrounded by tentacles. Coral tend to thrive best in colonies and make up the largest organic structures on earth.
Tropical seas are nearly devoid of nutrients, which is why the water is so clear. Reef building corals tend to thrive in tropical seas above 72° so how do they survive? In 1929 researcher C.M. Younge unravelled the largest cooperative relationship in the animal kingdom. In the stomach of each coral is living algae that takes advantage of photosynthesis and the corals respiration to produce usable nutrients and oxygen for the coral.
There are estimated to be over one thousand species of coral with some notable species dwelling as deep as fifteen thousand feet. As you snorkel or dive over our coral reefs here in the Bay Islands, you will readily pick out dozens of species just by their general shape. Pillar corals, Plate corals and the Gorgonians make up the biggest groups. Pillar coral colonies grow four to ten feet tall. Leaf and plate corals are the largest family making up the bulk of our reef and look more or less like their names imply. Gorgonians are made up of soft corals from the Octocoral family and have the appearance of denuded trees, with their long skinny branches.
Most corals are nocturnal, so their most interesting behaviour can be seen after dark when the feeding polyps extend. Corals can offer little in the way of offensive behaviour, but bumping into some can trigger a defensive one, leaving you with some nasty stinging nematocysts that will initially cling to your skin, and then discharge a painful venom if rubbed or if washed with fresh water. If you do contact coral, rinse the infected area with vinegar. You'll smell bad for a while and the scrape will still sting, but the damage to the coral will be worse.
March 20,2001
Strange Behavior
Like father like son! Nope, not in this ocean. One of the many interesting aspects of watching fish is picking out the juveniles and guessing what they will grow up to be. Many Reef fish begin life floating in a cloud high in the water column. After several weeks and possible thousands of miles, these tiny larvae float into shallow bays on incoming tides and settle in to start their lives as juveniles. You thought your childhood was tough! Most need to locate a specific type of bottom habitat to survive. Some settle on reef, some in sand and others in grass beds or mangrove. For the next few weeks they are virtually unidentifiable, and still small enough to be very difficult to see. Here are some of my favorites.
The Spotted Drum can first be identified as a crescent shaped wisp of fin with a nose and eyes. As the drum grows, a body starts to form forward of the fin, then the entire lower fin becomes body, with spots developing in adulthood. Drums are nocturnal feeders but can be found under ledges during the day.
The Sharp nose puffer is common all over the reef at varying depths. The adults are brownish green with white bellies and pointed little snouts. The juveniles can often be found inhabiting cracks and crevices of the Lettuce coral and resemble a little round spotted ball with eyes and fins the size of a pea.
Grey and French Angel juveniles are two of the most difficult to distinguish since the only variation between them is the cut of their tails. As juveniles they are both black with yellow stripes and actively clean parasites from larger fish. As they mature, they loose their stripes and take their place on the reef. While the French Angle is certainly more flamboyant with its golden tipped scales, the Grey is no less attractive and is very approachable.
An amazing pre-juvenile fish we often encounter on night dives is the Blue Tang. Its Ovaloid body is transparent except for a silver lining around its organs. As it develops into a juvenile it turns bright yellow, and then a deep vibrant blue in adulthood with a small yellow barb just before their tail fin. Blue Tangs are most frequently seen traveling and feeding on the reef in large schools.
April 12,2001
Strange Behavior
Farmers and architects are not necessarily two words we use to describe fish in every day conversation. The most common words are of course breaded or fried? When it comes to building a home and caring for a family however, we bipeds don't out do some fish by very much.
Damselfish are highly territorial, and will pick a piece of reef and defend it with their lives. The male damselfish selects and prepares a nesting site by removing debris and allowing filamentous algae to grow. Within and on the algae grow a small garden of diatoms and epiphytes that are the prime foodstuff of the Damsel. The male then goes looking for mates who will lay up to three egg clutches in the algae farm at a time, to be guarded by the male. During this farming and child-rearing period, the male damselfish will fearlessly attack anything that comes near, including divers. Fortunately for us damselfish seldom grow bigger than a few inches.
In terms of homebuilders however, Damsels have nothing on jaw fish. Jaw fish start their excavation by scooping out a six-inch deep hole in the sand using their mouth. They next bring in shells, rock and coral to build a tunnel like entranceway, below which they continues to excavate. When the final structure becomes cemented with sand a reinforced six inch long stone entranceway leads into a chamber about three inches high and as much as ten inches in diameter, limited mostly by immovable rocks. As if this behavior wasn't enough, these little guys also brood their young in their mouths. If you thought your kids were a handful, try raising them in your mouth.
Damselfish can be found everywhere on the reef. While there are several variety here in the Bay Islands, look for a dark blue or brown oval shaped fish chasing everything in the ocean away from their nest. The yellow headed jaw fish is the most common and are found on sand flats and in surge channels where they will most often be seen in search of materials or scooping sand out of their homes. Both Damsels and Jaw fish can be approached by divers or snorkels and will allow close observation if you remain motionless.