How to Tell the Different Rhinopias Species apart – Paddleflap, Weedy, Lacy

Rhinopias are rare fish that belong to the family of the scorpionfish and a must-see for every diver who likes weird critters and of course for underwater photographers.

They live in the Indian and Pacific oceans on the sea floor where they are well camouflaged to blend in with their surrounding. Therefore they are not easy for scuba divers to find, even for the weedy and paddleflap that are sitting on sand, rubble or rocky seabeds (muck diving).

All rhinopias have laterally compressed bodies with the eyes high on top of their heads and dermal appendages above the eyes, on the jaws and some also on the body surface.

Like other scorpionfish they wait camouflaged into their surrounding for the prey to approach, then they open the mouth very wide and suck the prey in. They are mostly hunting small fish and invertebrates at night.

By scuba divers during the day they can mostly be seen sitting around. They rarely swim (but they could if they wanted to)

but mostly move along the bottom in a hopping-like movement using their pelvic and pectoral fins to “walk”.

Posing for the picture? The Yawning

From time to time they yawn like it is known from other scorpionfish and frogfish. This is the moment the underwater photographer would like to capture.

It is assumed that they just do this movement every so long (like every half hour) and also that they do it more often when disturbed by the photographers and lights/flashes/sand pushed in their faces. Like always when diving close to the ground, make sure not to touch the ground, not even with your fins (you might hit a second rhinopias) and not to stir up sand.

They shed

A funny fact I found on one of the aquarium pages. I am definitely no friend of collecting animals from reefs (or anywhere else in the wild) to hold them at home, but people keeping specific fish at home often have additional information to what researchers and scuba divers find in the ocean. Rhinopias fetch high prices in the aquarium trade as they are such rare critters.

Rhinopias shed the outer epidermal layer (cuticle). This might help them to rid the body of algae, parasites and encrusting organisms. In the pictures below you can see the difference between a rhinopias full of algae and one without.

There are 6 known species of rhinopias, whereas only three are usually found by scuba divers. The most commonly seen are the “weedy” and the “paddleflap” rhinopias.

Rhinopias eschmeyeri, Eschmeyer’s scorpionfish, paddleflap Rhinopias or Scorpionfish

The paddleflap rhinopias has been first one to be described, as early as 1877. They can grow up to a bit over 20 cm in length.

Discussions have been raised if this and the weedy rhinopias really are separate species. In a following study the species have been confirmed and described in more detail. They can be told apart by the following 

Paddleflap:

• two tentacles on the underside of the lower jaw
• no tentacles below the eyes
• no distinct tentacles on the lateral surface
• short tentacles
• no distinct pigmentation or markings
• the first dorsal fin (the one on the back) is sail-like with no or only small incisions between the dorsal spines

Weedy/Lacy:

• many tentacles on the underside of the lower jaw
• 2-4 tentacles below the eyes
• distinct tentacles on the lateral surface
• long tentacles
• markings on the body
• deep incisions between the dorsal spines

The paper describes many more differences between the species, but I think the ones above are the easiest for us to use to tell them apart. The most common color to see this rhinopias is pale pink, but they can also be yellow, green, brown, pink, red and maybe more.

Rhinopias frondosa, weedy Rhinopia or scorpionfish

The weedy rhinopias was the first one to be described back in 1892. They can grow to the same size like the paddleflaps, which is a bit over 20 cm.

The weedys come in all kinds of colors, I have seen them in purple, red, yellow, brown and probably more.

The number of appendages varies with their habitat. Species living in algae rich environments have more weed-like appendages compared to the ones living around soft coral and sponges which have fewer appendages. Weedy Rhinopias with only a few appendaced might look more like the paddleflaps.

The weedy is also difficult to tell apart from the lacy Rhinopias. The easiest way to tell them apart are the markings.

• Weedy: circular and oblong dark-margined or pale spots, rings and blotches
• Lacy: elongate black-margined markings each with a central region of yellow, green or brown

Rhinopias aphanes, lacy Rhinopias or scorpionfish

The lacy rhinopias has been described by Eschmeyer as well like the paddleflap (or Rhinopias eschmeyeri) in 1973. They grow to the same size like the weedy and paddleflap. 

The lacy rhinopias are less often encountered by scuba divers as they can only be found in Papua New Guinea, New Caledonia, Vanuatu and northeastern Australia. So the ones that are encountered in Indonesia and the Philippines are always weedy.

And also the habitat differs between them. While paddleflap and weedy life in muck dive sites the lacy can be found on coral reefs mimicking crinoids (featherstars).

More Rhinopias

The other types of Rhinopias are rarely encountered by scuba divers. These are
Rhinopias argoliba (1973), found in Sagami Bay, Japan
Rhinopias cea (1997), possibly endemic to Easter Island
Rhinopias xenops (1905), the strange-eyed Rhinopias, Hawaii and Japan

Where to dive with Rhinopias?

The best destinations to see weedy and paddleflap rhinopias are Ambon, Alor and Bali in Indonesia. Less frequently they can be encountered in Anilao (Philippines) and Lembeh (Indonesia). The best place to see lacy rhinopias is Milne Bay (Papua New Guinea).

So which is which?

Let’s summarize how to tell the three most common rhinopias apart:

Paddleflap: Not many tentacles, single color, living on gravel or sand, Indian and Pacific Ocean

Weedy: Many tentacles, circles, living on gravel or sand, Indian and Pacific Ocean

Lacy: Many tentacles, elongated pattern, living in coral reefs around Papua New Guinea

And after reading all the information about how to tell them apart I go through my photos and for some I’m just not entirely sure. For example this yellow buddy:

For me it does look more like a weedy, but then there are not many circles, not many (but some) appendices and the color I have not seen for a paddleflap. What do you think?

Compared to this weedy:

Might they be the same after all? They can often be seen close together as well….

And what is that now:

Hipposcorpaena filamentosa, the similar to Rhinopias, but much smaller thing

When I was diving in Lembeh one of the guides found this weird thing everyone wanted to shoot. I was waiting forever it seemed, way above the critter to save some bottom time. When it was my turn I only had 3 minutes left before getting into deco. I had no clue what kind of critter I am taking pictures of, but it did look funny. After the dive we were told that this was a rhinopias. I wasn’t sure as the ones I have seen before did look different. Some people even claimed it was a baby rhinopias.

No, it wasn’t. It was a Hipposcorpaena filamentosus, another type of scorpionfish and the only one of its family. They do look similar to rhinopias and they behave similarly. This probably made people think it belonged to the same family. They look great anyway. I have only seen this critter twice, once in Lembeh and once in Alor. I heard that divers have seen it here in Bali too.

Have you ever seen a Rhinopias? Where? I would love to hear about all the places you found them – just leave a comment below