Cayman Marine Lab

The Mangrove Crab
The mangrove crab, Goniopsis cruentata, lives on and around the mangrove swamp. Their high tolerance to a variety of environmental conditions enables the exploitation of all the microhabitats such as mud banks, marshes, roots, and trunks of the trees. Typically dark brown with reddish appendages; this guy is very common but difficult to see because it is fast and sneaky. Most only live about 2 years and grow to around 6 centimeters in length. They range from Florida to Brasil in the western Atlantic and Senegal to Angola in the east.
Described as solitary and belligerent, they are always busy day or night either eating the mangroves or a variety of prey including smaller Mangrove Crabs. They play a vital role in mangrove ecosystem function by affecting the rate of decomposition of the leaves they feed on which is directly linked to nutrient cycling.

Overgrowing Mat Tunicate

The compound encrusting Ascidian (Tunicate), Trididemnum solidum, is very common on our coral reefs. A blue-green, leathery mat some 5mm thick and upwards of a couple of meters in surface area may cover and eventually kill portions of living coral heads as well as sponges.
The beauty and tranquility of the reef belie the real and constant turf-war taking place. Every organism is either fighting to maintain its property or attempting an expansion. A peaking order of dominance exists which is generally responsible for the fantastic diversity of life. The ingenious reproductive strategy employed by the mat tunicate has in some cases disrupted the balance. The tunicate develops numerous tadpole-like larvae which are released throughout the entire year. During the first few minutes of their fifteen-minute swim, they are attracted to light or the surface where currents are stronger and dispersal wider; signals change so they shun the light by swimming to the bottom. This same sequence occurs with many reef denizens however, unlike the others these larvae are very poisonous. Planktivorus fish have learned to avoid them and eat more of the other species' larvae. This same toxin gives the tunicate a leg-up on fighting to hold the new substrate they landed on and once a foothold has been secured the mat can expand very quickly – as much as thirteen centimeters a month, which smothers and kills. Noxious chemicals called didemnins repel any would-be predators and in studies where these mats were removed, it took just 6 weeks for colonies to return.
On a positive note, pharmacology studies have discovered that didemnins have powerful anti-inflammatory properties and are likely to be very beneficial to human health.

A while ago I nearly hit a half log while running 30 knots offshore. It is now a fish story

Silky Shark

The Silky Shark, Carcharhinus falciformis, of the family Charcharhinidae, is a true open water pelagic species; found all around the world in tropical waters. This dark-colored, sleek shark gets its name from its smooth, “silky” skin. They feed primarily on bony fish like tuna, and cephalopods like squid and are the most common species encountered by Cayman fishermen lucky enough to find offshore drifts. Gangs of very persistent three-footers or “pups” will surround offshore structures like our “FAD” fish attracting device – a couple of buoys tethered to the bottom surrounded by water approaching 10,000 feet deep. Adults who can reach a speed of nearly forty miles per hour and exceed 20 years of age are generally more solitary than juveniles.
Natural predators include bigger sharks and Killer Whales. Unfortunately, they are killed as a by-catch of the tuna fisheries and their populations have decreased substantially over the recent decades.

The Royal Gramma or Fairy Basslet, Gamma loreto, is a member of the family Grammidae. Although only three inches full grown their vibrant purple and yellow colors standout on the reef.
Native to the Caribbean, these shy fish prefer quiet, low light overhangs on the coral reef in 50 to 100-foot depths. They have a propensity to swim upside down, darting out short distances to engulf passing plankton. They are also known to be cleaners of other reef fish, meaning they will pluck dead tissue and eat parasites off their bodies.
All Royal Grammas are born female with one dominant fish in the small group becoming male.
It is always a treat to see divers doing headstands to have a good look at these beauties.

Cusk
The Cod-like Cusk, Brosome brosome, is a member of the family Lotidae. Found on both sides of the North Atlantic in deep cold waters, they feed on various small fish, crustaceans, and other soft-bodied invertebrates, including starfish. They are slow-growing and may reach four feet long and weigh over thirty pounds after 14 years.
Cusk has a firm white flesh that holds together well, making it a favorite for chowders and soups. Although not directly targeted, they are caught in trawls after more valued Cod, Haddock, and Pollack.
A heavy Norwegian metal jig fooled the specimen pictured, and it was hand-cranked from a depth of 340 feet.

The Atlantic Mackerel
The Atlantic Mackerel, Scomber scombrus, is found in tremendous and sustainable numbers in the temperate waters of the Mediterranean, Black Sea, and the northern Atlantic. They can grow to 24 inches and live for 18 years. Like many tuna-like species, they have retractable fins, powerful rigid tails, and tiny smooth scales, all of which facilitate speed. In addition, their distinct wavy black lines on a greenish-blue dorsal surface help them detect motion and confuse predators while schooling.
Over one million tonnes of these highly nutritious fish are caught each year. Mackerel are very easy to catch; even my dad could put my family of 8 on them. It wouldn’t take us long to fill a large plastic garbage bag. Our punishment was having to eat these oily fish for two meals a day all summer long. I should have asked Santa to bring me a smoker.

The Atlantic Cod
Cod, Gadus morhua, is the most important fish in the history of the world. As outlined in Kurlansky’s book entitled Cod, he points out how wars have been fought over it; revolutions have been triggered by it; economies and livelihoods have depended on it.
Cod can live up to 20 years and grow to 75 pounds. They are a big-headed, brownish, bottom feeder or groundfish that prefers a bottom with some structure. These indiscriminate feeders range from Greenland to North Carolina.
I am not alone in believing Cod is the best-tasting fish, which has led to their demise. They are now considered commercially extinct, so modern-day fishermen are said to be on the wrong side of a 1000 year fishing spree, which started with the Vikings.

Fluke
The Fluke or Summer Flounder, Platichthys dentatus, of the family Plueronectidae (Toothed Flounders) reside in coastal waters from Nova Scotia to the Carolinas. Like all flatfish, they are bottom dwellers with a white ventral surface and a brown dorsal side that instantly changes to match the ocean floor's color and texture. These chameleons of the sea are ambush predators feeding on various small fish, crustaceans, and squid.
Fluke grow quickly to a maximum size of three feet, and like their much bigger relative, the Halibut, they are delicious. As a result, an important and sustainable commercial and recreational fishery exists due to effective management efforts, leading to a ten-fold increase in biomass since 1990.