Halimeda

Common Name: Unknown - Cactus Alga? Coin Green?
Scientific Name: Genus Halimeda - Halimeda discoidea?

Family: Halimedaceae - Halimeda is the only genus
Class: Bryopsidophyceae - macroscopic green alga

Conservation status: Not yet assessed
Sighting: Ocasional

Identifying this species is very difficult for the amateur, as seems common with alga and seaweed. We think this beautiful alga is part of the genus Halimeda, but we can not narrow down to which species it really belongs. Lacking a good alga identification site, we have found pictures of Halimeda discoidea looking very similar, but then, some other H. discoidea pictures looked completely different, showing branches or segments of discs, which do not seem apparent in our pictures. It may well be some of the pictures are misidentified themselves, making the whole search even more challenging. 

In any case, Halimeda, described as a "green macroalgae, with a body (thallus) composed of calcified green segments", and the pictures of some of its species (it has more than 40 species listed, we didn't found examples of all), seem close enough to give us confidence we have the right genus.

Of the various common names we have found for species of this genus, green coin seem to be the most appropriate to this particular specimen. At least that is how we would describe it, they are the size of a US dollar quarter, but thicker, with a characteristic bright green rim. They do look like some Crassulacean plants (cactus without spines, if you want), therefore the "cactus alga" name, which also seem suited to this particular example.

FInally, in this -poor- video you can take a look how the colonies are interspersed within the turtle grass. You can also see a starfish featured in Cushion Starfish post, and the location of the area near Bill Baggs Cape lighthouse where you can find this species.

Look for an update on this page with better video, and hopefully full identification of the species. We will try to carefully analyze the stem structure, to see if it matches the descriptions.

Cushion Starfish

Common Name: Cushion sea star
Scientific Name: Oreaster reticulatus

Family: Oreasteridae - Heavily calcified, large bodies
Class: Asteroidea - True starfishes or sea stars

Conservation status: Not assessed
Sighting: Ocasional, in deeper shore waters.





You can find this beautiful large equinoderms in the edge of the swimming area in Bill Baggs Cape Florida State Park, near the lighthouse

Colors range from bright red to orange to pale yellow. They are large, about the size of one extended hand.
Taking this picture (actually a frame from the short video below) cost me a bad cramp on my left leg.

The tide was high, and the strong current forced me to keep swimming at full speed just to stay still. While trying to do a final push to get a close up picture, my left leg got cramped, really bad. Seconds after I was drifting at about 4 knots away, and I had to star swimming to the shore with only one leg. If you can picture limping while swimming, that was me. It was painful  but the fear of being drifted past the lighthouse point, into the open waters of Key Biscayne, was even worse. Doing a last effort, I reached with my hand to the sharp edges of the last rock in the point, and held there, hanging just from my hand while the rock cut my fingers, while the current pushed my body like a kite. After a couple of minutes, I could recover my breath, and finally made it safe to the shore, and my wife helped recover the cramped leg with her expert massage. A lesson about the strong tides in Bill Baggs Cape I wont forget easily!

I'll seek more of this beautiful animals, and will eventually replace this picture with a better one. There are plenty, but as they are in 5-10 feet (2-3 m) waters, light and water turbulence conditions are a challenge to get a good video or picture.

Update on 12/25 - I got a couple more pictures of beautiful cushion sea stars, as always, from the area in front of the Bill Bags lighthouse. The first one, more red in color, was beautiful, with heavily calcified spines on top.

The second one, yellowish, was huge, about a hand an a half (40 cm - 16 in) in size.

In this second one you can clearly see a paler circular structure, a bit off center - see enhanced picture below, and it is also visible in the red cushion star detail picture, above. This is the madreporite, basically a intake water control valve. You can find an excellent description, with schematic on how it works, and many more interesting details, in "The Echinoblog".

Yellow Ray

Common Name: Yellow Ray, or Yellow Stingray.
Scientific Name: Urobatis jamaicensis or Urolophus jamaicensis

Familiy: Urotrygonidae - Round rays
Class: Chondrichthyes - Cartilaginous fishes (sharks & rays)

Conservation status: Least concern
Sighting: Infrequent


Not really yellow, but brown with lighter and darker spots. We have seen this amazing fish a few times, always in the same are of the Virginia beach in Key Biscayne. It usually lays down on sand, motionless, in what seems cryptic behavior. We have also seen this behavior when it lays on top of turtle grass.

When it feels threatened, it swims away very quickly. We capture this in the video, below. In most cases, it first tries to "hide" in the environment, then starts swimming  as it notices our focus, and finally, it disappears in a fast swim. 

On another occasion we captured two of them together. In the camera. They are sting rays, so you want to stay a bit apart from them.

According to the Marine Species identification portal, it could be 1.2 to 1.8 meter wide. The ones we have seen are much smaller than that. Wikipedia mentions 70 cm (28 in) long. All the specimens we have seen are more about a foot (30 cm). Probably juveniles, that close to the shore.

We are still trying to see if it changes color, like cuttlefish, or not. Wikipedia mentions they could change coloration in response to the environment, but we have not been able to see that in the videos. So far.

All in all a very exciting sight!.

Paddle blade alga

Common Name: Fan Alga, soft fan alga, Paddle blade alga
Scientific Name: Avrainvillea nigricans (maybe Udotea flabellum?)

Family: Udoteaceae - tropical, calcified alga
Class: Bryopsidophyceae - macroscopic green alga

Conservation status: not yet assessed
Sighting: Occasionally, in sandy areas between turtle grass beds.

We have seen plenty of this beautiful alga in the sandy areas of Crandon park in Key Biscayne. It is a mesmerizing sighting, as they move in slow motion, back and forth, with the waves.

Classifying this one has been a bit challenging. We are unclear if this is the Paddle blade alga (our best bet) or the fan alga. Pictures look similar, and there are some not very encouraging indications "Positive identification requires laboratory examination of the specimens."

We settle for Paddle blade alga, based on pictures and geographic distribution  if any reader can help provide a better identification, we will appreciate.

Turtle Grass

Common Name: Turtle Grass
Scientific Name: Thalassia testudinum

Family: Hydrocharitaceae - aquatic plants
Class: Angiospermae - flowering plants

Conservation status: Least concern, population stable
Sighting: Very frequent, all over Biscayne Key

Turtle grass is the first thing you'll find when you snorkel in Key Biscayne. It is specially abundant in Bill Baggs Cape Park, starting a few feet from the shore. Also in Crandon park, as soon as the sand starts to get covered by green, that is mainly Turtle Grass.
After a strong storm, you will also find large amounts of turtle grass leaves in the seashore, creating a brown dam, in same cases up to a couple feet high.  

As you can read in the links, turtle grass is actually a flowering plan, growing from a rhizome. The name comes form the Green turtle (Chelonia mydas), that feeds on the grass, although is a natural habitat for many animals, and feeds multiple herbivorous fishes of the florida waters, some of which eat the algae that grows in their leaves, rather than the seaweed itself. And of course, manatees graze turtle grass!

Although it looks uneventful, almost boring, if you look carefully, you can discover a variety of creatures hiding in the beds of turtle grass. Starting with other seaweeds and algae, sponges, crabs, conchs, and many different solitary swimming fishes, like pufferfishes. 

In the Crandon park area, turtle grass grows large, specially in the shallow waters on the left of the main beach, by the natural park protected areas.

The interface between the higher beds of turtle grass and the clear sand , like the one in the picture at the right, are also great areas to see all sorts of fish, hiding in the dark shadows created by the turtle grass. If you are patient and quiet, once your the shock for your presence is over, small and larger fishes will start swimming out of the shadows, making for a great beginner snorkeling experience.

Blue Crab

Blue Crab Hiding in Seaweed

Common Name: Blue Crab
Scientific Name: Callinectes sapidus
Family: Portunidae - swiming crabs
Class: Malacostraca - Main crustacean class: lobsters, shrimps, crabs... 

Conservation status: Not listed
Sighting: Frequent, in shallow, sandy waters.



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We have found several Blue Crabs, always alone. They are a fancy and lively sight, identified by the vividly distinctive blue colors of its legs. They quickly respond to our approach by switching into a rather enthusiastic defensive stance. They raise the front of their carapace, and snap their claws. Then, quickly, yet never letting down their guard, they scram sideways searching for a hiding spot among the seagrass, helped by the flapping of their seemingly ungraceful swimming legs.

This one was spotted buried in the sand, eyes sticking out like a periscope, and we almost stepped on it. Once his hiding place had been compromised, it swiftly raced to the seaweed bed on the border of the sand bank, where it stopped and spied on us.
We captured this on video!
After a while watching each other, it decided to seek refuge in the dense forest of turtle weeds, further from the dangers of the sand. Such as pelicans... and distracted humans.