Octopus and squid belong to a class of animals called cephalopods, or head and foot animals. They are mollusks, but lack the external shells of their snail and clam cousins.
The most common octopus at the Flower Garden Banks sanctuary is aptly referred to as the common octopus (Octopus vulgaris). However, this video shows a Caribbean two-spot octopus (Octopus filosus) out hunting in broad daylight, which is rather an unusual occurrence.
The video begins with the Caribbean two-spot octopus crawling and "jetting" (pushing itself forward by expelling a stream of water) across the reef with a file clam clasped in its tentacles. As the octopus flees the camera, it rapidly and repeatedly changes its color and pattern. Only in certain color combinations are the two spots visible that give it it's name. Outside of the den where the octopus disappears with its prey, you can see the leftovers of other file clams scattered about the reef. Piles of shell discards (middens), like these, often indicate where an octopus lives.
The end of this video shows brief clips of two small squid (probably Loligo plei) seen swimming up in the water column at night.
While there are many different kinds of invertebrates found in a coral reef environment, they are not always easy to find. They tend to hide in the nooks and crannies of the reef as a means of avoiding predators. Many of them only venture out of their hiding places at night.
This video provides a glimpse of a variety of fascinating invertebrates found at Flower Garden Banks National Marine Sanctuary: banded coral shrimp feeding; slipper lobster crawling across the reef; decorator crab moving across the reef; file clam filtering water with shells open and tentacles extended; brittle star snaking its way across open coral polyps at night; slipper lobster crossing the flats at Stetson Bank; decorator crab crawling around between corals; close-up of a queen conch probing the sand with its proboscis; axiid lobster extending its gills outside its burrow; long-spine sea urchin waving its spines around amid a group of cardinalfish; banded coral shrimp snatching plankton; bristle worm crawling slowly cross a brain coral colony.
Jellies, like coral polyps, belong to the scientific group of animals known as Cnidaria (ni-day-ree-a). This video highlights the graceful, pulsing movements of moon jellies. Like coral, they may also provide shelter for other animals, as seen in the second half of the video. The small fish swimming under the moon jelly's bell are believed to be juvenile jacks.
Sea hares are often referred to as shell-less snails, although they do actually have small internal shells. The species in this video is relatively large, ranging up to 10 inches in length. Each sea hare has two pairs of rolled tentacles--a pair near the mouth, which it appears to use for feeding, and a pair called rhinophores on top of the head.
This video shows sea hares swimming over the algae-covered bottom at Stetson Bank by flapping the large, fleshy extensions of their mantles like wings. They were probably attracted to Stetson Bank because of all the algae, their primary food.
This discussion was part of a presentation on invasive species that was given by Dr. Michelle Johnston, a sanctuary researcher, during the sanctuary's Seaside Chat series in 2012.
Transcript: Invasive cup coral. This is a native species to the Indo-Pacific, so it comes from the Pacific Ocean, and it was thought to get here probably through ballast water on big tanker ships. As the ballast water is dispelled the coral or the larvae of the coral was dispelled here in the Gulf, as well. Those larvae then took up residence on the reefs, but probably more likely on the oil and gas platforms.
So these are very common on the oil and gas platforms here in the Gulf and it's been thought that the oil and gas platforms actually act as stepping stones. So, when the larvae are dispelled when these guys reproduce, then the currents take them to the nearest platform. And then it happens again and takes them to the next platform. It's kind of worked its way around the Gulf.
The cup coral is now at the Flower Gardens. It isn't prolific, it isn't everywhere, but we do have areas at the Flower Gardens where there's actually walls of this stuff. Even though it's beautiful, it's colorful, bright orange, and it looks really pretty, this is fast growing and it competes for space with our native corals, and out-competes our native corals. It's actually a bad thing because we want our native corals, our brain, our star corals, to be growing and not the cup coral.