This week, I saw and captured pictures and video of a gorgeous Gulf sand Flounder. I am still new to identifying all of my reef friends but with my trusty REEF Net CD, I easily looked this up. I have seen these fish shore diving and snorkeling. The ones I see are generally over a foot. Very graceful, like they are floating on air.
The Gulf Sand Flounder has an elongate tan to brownish body, often with a smattering of brown or pale rings with dark spots at their centers, and often with 2 or 3 dark spots on the lateral line: one near the pectoral fin, another near the tail base, and sometimes a third one between them. Usually these will form a triangle on the body surface . There may also be broad dark lines between the eyes. The gulf flounder body color is generally brown overall, and can vary in shade depending on the color of the substratum. The one I saw in the sand was more of a gray brown.
The gulf flounder hatches into a usual fish form, but the right eye eventually migrates over to the left side. The blindside is white or dusky. This fish is up to 2 lbs. and 15 inches long. The Gulf Flounder has strong canine-like teeth and feeds on crustaceans and small fishes. Although flounder will strike artificial baits such as jigs and gold spoons, live bait such as small, live shrimp, mud minnows and finger mullet is far more effective to catch them. These fish are found on soft bottoms in calm and shallow water and also found in grassy refuges or patches of rock and pebbles. The one I spotted was right before the first reef patch in Pepper Park in the sift sand. In specimens less than 5 inches long the eye separation is less than 15% of the eye diameter.
This type is close to a dusky flounder which has very little spotting on the body and eyes further apart.
This is a bottom-dweller in shallow (to 40 feet) sand, grass, and coral rubble areas, often in bays, harbors, and channels (hence the common name). However, it has been reported from as deep as 1200 feet. It either lies motionless, matching its color to that of the bottom, or glides along the bottom by undulating its dorsal and anal fins. It is easy to approach closely. I got right up close and personal with the one this week. He was not too fast and it was easy to enjoy watching him.
For protection and predation they rely on camouflage. This little guy as you can see scooted under the sans while I was watching him. Because of the pigmentation on their upper (eyed) side, they are excellent color changers that can blend perfectly with the bottom coloration. Often they will bury themselves in the sand with only their eyes exposed. When a small fish or crustacean comes near the flounder darts out and catches it.
There are 16 genera and at least 85 species of sand flounders in the tropical to temperate waters of the Atlantic, Indian, and Pacific Oceans (and occasionally in fresh water). They are very compressed fishes (‘flatfishes’) usually having both eyes and pigmentation on the left side of the body, a long dorsal fin that extends onto the head at least to the eyes, spineless dorsal and anal fins, short pelvic fin bases, and branched pectoral fin rays. The pectoral fin on the blind side is occasionally absent. The pelvic fin bases may be symmetrically placed on either side of the ventral midline, or asymmetrically placed with the base of ocular-side fin on the ventral midline and the base of the blind-side fin slightly off to the side. Each pelvic fin has 6 (rarely 5) soft rays and no spines.
The Gulf Flounder is a paralichthyids. This means it will produce many pelagic eggs that disperse on the ocean surface. The larvae are initially left-right symmetric, but at some point during their development they undergo a metamorphosis: the right eye migrates through the head onto the left side of the body, passing through a slit below the base of the dorsal fin; the mouth usually shifts to that side; and the internal organs undergo some rearrangement. At this point, the larvae descend to a soft bottom, where they flip over onto their blind side and begin their existence as bottom dwellers.