
There’s a scene in Creature from the Black Lagoon (1954) where Kay Lawrence (Julie Adams) is discussing evolutionary throw-backs and blurts out the name Kamongo as fortification that an amphibious man might exist. When I was a kid I always thought that the writers had screwed up. After all, I couldn’t find “Kamongo” in the Encyclopedia Britannica and it wasn’t in the Time Life nature books, and I never heard of Marlin Perkins wresting one either.
I was sure they were talking about the monstrous living-fossil fish Latimeria, also known as the Coelacanth. Latimeria is a Lazarus Taxon —a group of organisms that disappears from the fossil record, only to reappear again later. The Coelacanth is a living fossil and it fit to a T what smoking hot ichthyologist Julie Adams was talking about. Much later, in graduate school, I took an ichthyology class for giggles (and because the girls in the class were all scuba divers with hot bodies) and found out that the Kamongo did and does indeed exist. It’s the local name for the African lungfish (Genus Protopterus, containing 4 species). Kamongo is the equivalent to the colloquial “Grinnell” that American southerners apply to the ancient Bowfin fish (Amia calva). They’re considered a food fish. Here’s an image of a fellow getting ready to filet a Kamongo.

Lungfishes are an interesting group of organisms. They are successful vertebrates stemming back to the Early Devonian Period (approximately 410 million years ago). The Marbled Lungfish (P. aethiopicus) has the largest genome of any vertebrate on the planet (133 billion base pairs). There’s also an Australian Lungfish (Genus Neoceratodus) that is related to the Coelacanth in being in the very ancient group Sarcopterygii (fleshy finned fishes). African and Australian Lungfishes are examples of convergent evolution —two groups possessing the same biological traits in unrelated lineages. Perhaps there is a proto-lungfish in the fossil record that links the two.
The concept of convergent evolution brings us to the story of the Gill-man. Could an amphibious fish-like humanoid exist? The Creature is an interesting fellow. He’s bi-pedal, possesses cephalization (has a distinct head), has bilateral symmetry, uses tools, “remembers the past and more,” and has a crush on Julie Adams. These are traits of humans and perhaps earlier hominids. He also possesses a hard dermal (possibly ossified) outer layer, splayed webbed feet and hands, gills and protective covering on his eyes (nictitating membranes like a shark or crocodilian). These are fish-like traits. The Gill-man is essentially a fish that convergently evolved like a man. His ancestors would be fleshy-lobed fishes like the lungfish and Coelacanth.
Creature from the Black Lagoon is a well-made and beloved 50’s classic. I think it is also intelligent. Carl Maia (Antonio Moreno) plays a geologist. He refers to limestone deposits, which is exactly where fossils might be found. He offers up the idea that fluctuating water levels may have eroded away the Gill-man fossil and transported it downstream. I’m not sure why the lagoon is downstream, unless the river is impounded. I also like the crew. Like all good seamen, Capt. Lucas (played by the incomparable Nestor Paiva) is improvisational and comes up with a unique way to deal with the Gill-man. Rotenone!
In the film, the crew of the Rita just happens to have some Rotenone (I think Lucas is a poacher), but it is actually derived from several plants. The fuzzy, ubiquitous weed Mullein (Verbascum thapsus), shown in my half-dead lawn, contains trace amounts of rotenone and coumarin (now you can go knock off your spouse).

Rickard Carlson is also believable as ichthyologist David Peel. The writers give him a few dumb comments: “….could it belong to a pleistocene man?”. Nope that’s clearly the claw of an amphibious bi-pedal fish-man. I also laugh when I see schools of fishes in the crystal clear Amazon tributary —look quick for the bullheads swimming about! And then there’s that ubiquitous Australian Kookaburra that got lost in the Amazon Basin!
http://en.wikipedia.org/wiki/Protopterus