Can’t identify this and the suggestion identifies duties as a sea turtle, which it was not. This 12” long creature was seen swimming in the salt water. The flaps continuously opened and closed approx every 5 seconds and the “front end” appeared to come up and go down as if it needed to do that to breathe or feed. It was swimming along the surface of the water.

Dryspteris abortivaria #26199
Det. John L. Sperry
Florida City, Florida.
15 October 1937, Mrs. Forsyth

Grand Canyon Museum Collection
2 Albright Ave, Grand Canyon Village, AZ 86023
Phone: (928) 638-7769
https://www.nps.gov/grca/learn/historyculture/muscol.htm

Lygris diversilineata #26223 Det. John L. Sperry Florida City, Florida. 31 May 1937, Mrs. L.E. Forsyth

Grand Canyon Museum Collection
2 Albright Ave, Grand Canyon Village, AZ 86023
Phone: (928) 638-7769
https://www.nps.gov/grca/learn/historyculture/muscol.htm

Coryphellina marcusorum (Gosliner & Kuzirian) was described from the eastern Pacific. Phylogenetic testing has not been done to determine if the western Atlantic animal is a reproductively isolated population functioning as a distinct species.

The animal was located on top of reef at a depth of 5 feet. Length was 0.7 cm. Water temperature was 82 degrees F.

Navanax aenigmaticus (Bergh, 1894) was described from the eastern Pacific Ocean. This animal was located in the western Atlantic and is called N. aenigmaticus in accord with the most recent taxonomic guide of the Caribbean (Valdés, Hamman, Behrens & DuPont, 2005), but note that Valdés et al. (2005) indicates that taxonomic placement is uncertain because phylogenetic study is lacking. Recent biogeographical studies using DNA have found that populations of tropical species in the eastern Pacific and western Atlantic are separate species.

Substrate was algae-covered coral rubble in the lee of the reef. Depth was 15 feet. Water temperature was 84 degrees F.

Flabellina sp. 3 is undescribed. See the identification guide Caribbean Sea Slugs by Valdés, Hamann, Behrens and DuPont (2005).

This animal was located on reef at a depth of 5 feet. Multiple individuals were observed and length varied from 0.5 to 1 cm. Water temperature was 82 degrees F.