Coral Reefs (2)

Tropical Coral Reefs (continued)

Back again to the underwater world of the coral reef.

There are more species on a coral reef than on any other underwater habitat. Part of the reason for this is that the fundamental structure or architecture of the reef is not rock, but is instead corals and coralline algae. That is, the structure itself is alive! This means that the living part of the habitat can adapt and be influenced by the creatures that live within it. This is an organic matrix, and it makes the diversity skyrocket.

So here are some more underwater coral reef critters.

Gorgonians and corals are closely related. In fact, the main difference between them is the "skeleton." In corals it is calcareous, but in gorgonians it is a material, something like your hair, called keratin. In this case, the keratin is a tough and very flexible material, perfect for a branching, tree-like structure. Behold -- a gorgonian.

The green moray is the largest Caribbean moray eel. Moray eels are fish, not snakes, and have gills. Their fins are reduced to a more-or-less continuous band from just behind the head all the way around the tail and back up to just under the belly. Their skin is velvety smooth and adapted for slithering in caves. Their elongate nostril replaces their eyes for sensing prey in the dark.

Here is the eye of a stingray, peeking out of the sand. This is the Caribbean round stingray, a small species reaching little more than 50 cm (2 feet) in length. But it packs a wallop if you are so unlucky as to make it mad enough to jab you with its 8 cm (3 inch) barb.

Sponges are among the most primitive of the large coral reef animals. The vase sponge is one typical shape, its walls full of small pores through wich it sucks water. It filters the water to remove the plankton -- on which it feeds -- and then pumps it out the big hole that forms the vase. If you are a diver, you can actually feel the gentle current of water coming from some of the sponges.

Lots of fish on reefs make quick changes in their character and food habits, but here is one that does it slowly. The yellowtail snapper begins life as a plankton-feeder, swimming high off the reef until it is quite large -- a full adult. Slowly then, it chooses a different habit and moves to the reef-top, and there it begins feeding on larger animals under cover of darkness.

This brilliant orange Ascelus sponge is home to a small parazooanthid commensal. To put that into English, the "orange swiss cheese" is a sponge that lives by cementing itself flattened onto the rock or coral surface. The little blue spots are another animal, a small parazooanthid, that lives with the sponge. The sponge is not damaged but the parazooanthid benefits by living in water currents that draw in plankton for both of them to feed on.

This purple sponge is a wonderful rich magenta color, but in deep water in natural light, it appears to be merely a dusky blue. This colour difference is because the red is filtered out as the sunlight passes through the water.

Both the orange vase sponges and the branched yellow fire coral are animals. But the sponges are passive eaters of plankton, filtered from the water they siphon through their pores, whereas the fire coral uses five different kinds of stingers to kill, stab, and ensnare its prey. The fire coral's several different types of tentacles indicate that it is not a true coral, although related.

This frilly creature, a deep water demosponge, is a relatively rare species in the Caribbean. Although it is hard to the touch, its frills are quite fragile.

For such a beautiful butterfly fish, it has two quite ugly names: the melon butterflyfish and the lineated butterfly fish. I actually like the scientific name better: Chaetodon trifasciatus.

The turkeyfish and its relative the lionfish are popular aquarium fish. But beware: these are members of the scorpionfish family, and even a minor scratch from one of the thirteen dorsal spines can carry a painful and even dangerous dose of venom.

I know, I know, its time to see another shark. Well here you are: a Caribbean reef shark. Notice the sculptural lines on the head. These fish slice through the water with elegant efficiency. Their nostrils are capable of sensing amazingly low concentrations of blood in the water.

Like a kind of animated slurp gun, the jaws of the trumpetfish are designed to shoot almost half again as far as their length. This trick really takes unsuspecting prey by surprise, especially when the trumpetfish is so slim and presents such a small and unthreatening aspect from head on.

The long-spined soldierfish makes a deep drumming sound with which it expresses annoyance when a diver gets too close, forcing it to duck into its little cave. At night the soldierfish leaves the reef's protection and takes off for the open water to hunt.

Contact us: home@kivu.com

	Gorgonians and corals are closely related. In fact, the main difference between them is the "skeleton." In corals it is calcareous, but in gorgonians it is a material, something like your hair, called keratin. In this case, the keratin is a tough and very flexible material, perfect for a branching, tree-like structure. Behold -- a gorgonian.
	The green moray is the largest Caribbean moray eel. Moray eels are fish, not snakes, and have gills. Their fins are reduced to a more-or-less continuous band from just behind the head all the way around the tail and back up to just under the belly. Their skin is velvety smooth and adapted for slithering in caves. Their elongate nostril replaces their eyes for sensing prey in the dark.
	Here is the eye of a stingray, peeking out of the sand. This is the Caribbean round stingray, a small species reaching little more than 50 cm (2 feet) in length. But it packs a wallop if you are so unlucky as to make it mad enough to jab you with its 8 cm (3 inch) barb.
	Sponges are among the most primitive of the large coral reef animals. The vase sponge is one typical shape, its walls full of small pores through wich it sucks water. It filters the water to remove the plankton -- on which it feeds -- and then pumps it out the big hole that forms the vase. If you are a diver, you can actually feel the gentle current of water coming from some of the sponges.
	Lots of fish on reefs make quick changes in their character and food habits, but here is one that does it slowly. The yellowtail snapper begins life as a plankton-feeder, swimming high off the reef until it is quite large -- a full adult. Slowly then, it chooses a different habit and moves to the reef-top, and there it begins feeding on larger animals under cover of darkness.
	This brilliant orange Ascelus sponge is home to a small parazooanthid commensal. To put that into English, the "orange swiss cheese" is a sponge that lives by cementing itself flattened onto the rock or coral surface. The little blue spots are another animal, a small parazooanthid, that lives with the sponge. The sponge is not damaged but the parazooanthid benefits by living in water currents that draw in plankton for both of them to feed on.
	This purple sponge is a wonderful rich magenta color, but in deep water in natural light, it appears to be merely a dusky blue. This colour difference is because the red is filtered out as the sunlight passes through the water.
	Both the orange vase sponges and the branched yellow fire coral are animals. But the sponges are passive eaters of plankton, filtered from the water they siphon through their pores, whereas the fire coral uses five different kinds of stingers to kill, stab, and ensnare its prey. The fire coral's several different types of tentacles indicate that it is not a true coral, although related.
	This frilly creature, a deep water demosponge, is a relatively rare species in the Caribbean. Although it is hard to the touch, its frills are quite fragile.
	For such a beautiful butterfly fish, it has two quite ugly names: the melon butterflyfish and the lineated butterfly fish. I actually like the scientific name better: Chaetodon trifasciatus.
	The turkeyfish and its relative the lionfish are popular aquarium fish. But beware: these are members of the scorpionfish family, and even a minor scratch from one of the thirteen dorsal spines can carry a painful and even dangerous dose of venom.
	I know, I know, its time to see another shark. Well here you are: a Caribbean reef shark. Notice the sculptural lines on the head. These fish slice through the water with elegant efficiency. Their nostrils are capable of sensing amazingly low concentrations of blood in the water.
	Like a kind of animated slurp gun, the jaws of the trumpetfish are designed to shoot almost half again as far as their length. This trick really takes unsuspecting prey by surprise, especially when the trumpetfish is so slim and presents such a small and unthreatening aspect from head on.
	The long-spined soldierfish makes a deep drumming sound with which it expresses annoyance when a diver gets too close, forcing it to duck into its little cave. At night the soldierfish leaves the reef's protection and takes off for the open water to hunt.