Synodus intermedius facts for kids
Quick facts for kids Synodus intermedius |
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| Scientific classification | |
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Aulopiformes
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| Family: |
Synodontidae
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| Genus: |
Synodus
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| Species: |
S. intermedius
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| Binomial name | |
| Synodus intermedius (Spix & Agassiz, 1829)
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The common sand diver (Synodus intermedius) is a type of fish that belongs to the lizardfish family. These fish are a kind of ray-finned fish, which means they have fins supported by bony rays. Sand divers live in warm ocean areas, usually between 37 and 17 degrees North latitude.
You can find them in sandy parts of the ocean floor, near coral reefs, in bays, and even in river mouths (estuaries). They are called "demersal" or "benthic" fish because they live on or very close to the seabed. Common sand divers are found from the northern Gulf of Mexico down to the Guianas, and north along the western Atlantic coast to North Carolina and Bermuda. They are very common in the Caribbean Sea. These fish can grow up to about 40 cm (16 inches) long and weigh around 1 kg (2.2 pounds).
Sand divers have a pale body, usually gray to brownish-gray, with mottled (blotchy) patterns on their head and body. Their belly is whitish. They have different markings, like a black spot near their shoulder and reddish-brown stripes across their back. Thin yellow-gold lines run along their sides, from behind their gill cover to the base of their tail fin. These fish can even change their color to become lighter or darker, helping them blend in with their surroundings.
What's in a Name?
The name Synodus comes from Greek words. Syn means "grown together," and odous means "teeth." This name likely refers to how their teeth are arranged.
In English, this fish is commonly called the "sand diver" or "lizardfish." In French, it's known as anoli de sable. In Spanish, it has many names, such as chile manchado, doncella, guaripete, guavina, lagarto gigante, lagarto mato, lagarto manchado, or manuelito.
Fish Family Tree
Lizardfishes belong to a group of fish called Aulopiformes. In the western Atlantic Ocean, there are three main groups (genera) of lizardfishes: Synodus, Saurida, and Trachinocephalus. The Synodus group has six different species, Saurida has four, and Trachinocephalus has just one.
Scientists have found fossils that show fish similar to lizardfishes have been around for a very long time, possibly since the Early Cretaceous or Late Jurassic periods. That's millions of years ago! Most of the families of these fish that we see today appeared by the Late Cretaceous to the Eocene. Lizardfishes are a small group of fish that live on the ocean floor, often near coral reefs and continental shelves.
How to Spot a Sand Diver
Sand divers have a long, slender body and can grow up to 46 cm (18 inches) long. Their upper body is a mottled brownish-gray. They have a black spot on their shoulder, near the top of their gill slits. You can also see about eight pairs of reddish-brown bars across their back and sides. These bars are widest near the lateral line (a sensory line along the fish's side) and get narrower towards their belly. They also have thin, yellowish-gold lines running lengthwise along their body. The underside of the fish is pale.
To tell a sand diver apart from other similar fish:
- Its lower jaw is rounded and doesn't have a fleshy bump.
- The front part of its dorsal fin (top fin) is relatively short.
- The anal fin (bottom fin near the tail) has 10 to 12 soft rays. This helps tell it apart from the diamond lizardfish (S. synodus), which has 8 to 10 rays.
- It's sometimes confused with the Atlantic lizardfish (S. saurus), but that fish is rare in the Caribbean and has thin, blue or turquoise lines.
Like many fish that live on the seabed, the sand diver's eye has a special shiny layer. This layer might help protect its eyes from very bright light. Its mouth is wide and full of many sharp, needle-like teeth. It has two rows of teeth in its upper jaw, with the inner teeth being longer. In the lower jaw, there are three rows of teeth. The outer row is covered by its lips, and the middle teeth get bigger. Both jaws have teeth at the back that lean slightly backward. Even its tongue has five rows of teeth, with the largest ones at the front, also leaning backward!
Where They Live
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Sand divers live in the warm waters of the western Atlantic Ocean, the Caribbean Sea, and the Gulf of Mexico. Their home ranges from North Carolina and Bermuda, all the way south to Santa Catarina in Brazil. They are also found throughout the West Indies and the northern, eastern, and southern parts of the Gulf of Mexico.
These fish usually live on or near the seabed in sandy areas. You might find them among rocks or in sandy paths within reefs. They also like to rest on top of reef structures, propping themselves up on their pectoral fins (the fins on their sides). Sand divers can be found at depths of up to 320 meters (1,050 feet). However, they don't usually live close to the shore. Most often, they are found at depths between 38 and 110 meters (125 to 360 feet).
What They Eat
Sand divers are predators that eat other fish. They are ambush predators, meaning they wait quietly for their prey to come close. They were once thought to be "mid-level" predators, but now we know they are actually high-level hunters that actively chase and eat other predatory fish. In some places, they are even considered apex predators, meaning they are at the very top of the food chain.
You can find them resting on top of the sand or on reefs. They can also bury themselves in the sand, leaving only their heads sticking out, ready to surprise their prey. Sand divers mainly eat other bony fish. They also feed on crustaceans (like crabs and shrimp) and cephalopods (like squid and cuttlefish).
