Snorkeling on Day Two

Tuesday morning, June 30, 2015, we started the day with a brief lecture on general anatomy of reef organisms. Professor Gilchrist spoke of the three levels of organization; cellular, tissue, and organ, and spoke of the controversy surrounding whether sponges are on the cellular or tissue level. It was concluded that they can be either depending on the species. We were introduced to three species of sponges that we would likely be seeing on the reef later in the day. The first species, the asconoid is on average less than one centimeter in length and has a single dermal layer with non cooperating parts. This sponge species is on the cellular level. The second species we learned about is called a syconoid sponge and is a bit more complex than the last. It has flagellant cells that cooperate to bring water and food into the central area. The osculum pushes water out and the ostium brings water in. The most complex species we discussed is called the leuconoid and is on the tissue level. This species has distinct chambers and the cells within the chamber cooperate to move particles. One fact that I found particularly interesting was that sponges are an entity meaning they can recognize self. If two different species cells were mixed up, the individual species would be able to segregate to others of their own and grow from fragments.

Like sponges, corals have cellular and tissues levels as well. Their primary tissue is in the core, called the gastrovascular cavity. This location serves as a place where material is brought in and digested and where water is collected and moved out. Corals are considered truly colonial and have different growth forms depending on their location. Soft corals are often erect and have photosynthetic pigmentations other than chlorophyll. They rely on polyps stinging their food and bringing it into the gastrovascular cavity. This species is crepuscular and is highly active before dawn and after dusk. This is because zooplankton is most active during this time. Corals may also grow in plate formations to increase their surface area for photosynthesis in deeper water. Corals that can be found 40 plus feet below are non-colony forming and are called solitary corals.

I am fascinated by the relationship that hermit crabs have with soft corals. They use the soft corals for elevation and pick mucus off, eat the polyps, and defend parts of the soft coral from other organisms such as anthropods. Soft corals are also home to brittle stars, basket stars, anemones, and worms. We reviewed common species of worms that would be seen on the reef. The most common species the polychaete (fire worm) can be either errant of non-errant. Errant species are free roaming and are not connected to tubes like the non-errant species are. These worms have bristles in their structure. Oligochaete are similar to earth worms. They do not have a fancy structure and also have small bristles that stick out from their sides.

There are two species of octopus that are common on the reef we will be snorkeling today. One is called the common octopus, Octopus vulgaris and the other is the Octopus briarieus. We were informed of distinguishing features between the two and were told to be observant of the webbing between the tentacles. The common octopus has a much shorter web than the Octopus briaries. The Octopus briaries also has a blue tinge around its eyes and cups of its suckers.

On our morning snorkel we explored the House Reef. This reef appeared healthy and had a plethora of species to be seen. I saw many fire corals, some with branching growth patterns and others with box and blade growth patterns. I noticed encrusting common sea fans on many of the branching fire coral (Millepora alcicornis). I was also able to identify dichotomous and lateral branching on soft corals as well as interconnected net-like branching. After checking the Reef Coral Identification guide I was able to identify the following coral species:

• Brilliant Sea Fingers (Tiranideum frauenfeldii) 
• Elkhorn Coral (colonies growing in shallow water, did not have long wide flattened branches like colonies growing in moderate depths develop) 
• Symmetrical Brain Coral (Pseudodiploria strigosa) 
• Black Coral (unsure of species) 
• Sea Rods (unsure of species) 
• Sea Plumes (unsure of species) 
• Giant Anemone (Condylactis gigantea) 
• Sea Walnut (Mnemiopsis mccradyi) 
• Caribbean Spiny Lobster 
• Mysids 
• Flamingo Tongue 
• Cushion Sea Star (Oreaster reticulatus) 
• Magnificent Urchin (Astropyga magnifica) 
• West Indian Sea Egg (Tripneustes ventricosus)

I also saw the following fishes: 

• Tiger Grouper (Mycteroperca tigris) 
• Sand Perch (Diplectrum formosum) 
• Red Band Parrotfish (Sparisoma aurofrenatum) 
• Yellowtail Parrotfish (Sparisoma rubripinne) 
• Green Moray (Gymnothorax funebris) 

When we went snorkeling later in the afternoon we explored a reef that was closer to shore. This reef did not appear to be as healthy as the first ones we looked at. I noticed many bleached species and a few Flamingo Tongues (Cyphoma gibbosum) feeding on Sea Fans. One species that stood out to me was the Christmas Tree Worm (Spirobranchus giganteus). This worm has varying colors and markings and is highly sensitive to movement. When it senses movement nearby it retracts crowns and closes its oberculum. After the movement has passes the radioles emerge very slowly.

I identified the follow species:

• Giant Anemone (Condylactis gigantea) 
• Sea Walnut (Mnemiopsis mccradyi) 
• Caribbean Spiny Lobster 
• Mysids 
• Flamingo Tongue 
• Cushion Sea Star (Oreaster reticulatus) 
• Magnificent Urchin (Astropyga magnifica) 
• West Indian Sea Egg (Tripneustes ventricosus)

Turtle Grass