Sharks & Rays

Group 12: Sharks & Rays

Sharks & Rays

Group 12 - Sharks & Rays : Even though the sharks and rays are cartilaginous (their skeletons are made of cartilage instead of bones), they are still referred to as fish and count during our surveys.

Round Stingray (raya redonda, Urobatis halleri)

This ray is most often found away from the reef on sandy and silty bottoms. The ID can be confirmed by the small lines around the round wings of the ray and the lack of body spots. Two other similarly looking species occur in the area, Urobatis maculatus (Spotted Stingray or Cortez Round Stingray) and Urobatis concetricus (Bullseye Stingray or Concentric Stingray). Please consult reference guides before recording a stingray on the scanform. (Max disk size 12”, Max length 16”)

Manta Ray (manta, Manta birostris)

Mantas are the gentle winged giants of the sea. Positively identified by the protruding cephalic fins on either side of the head, mantas have mouths at the front of the head, rather than underneath like other rays. There are a few other, smaller species of Mobula, a ray similar in appearance to the manta, that are found in the Gulf. You are most likely to see the mobula jumping out of the water while you are on the boat, rather than underwater. Both mobula and manta are harvested in the Gulf of California and their populations have decreased dramatically. (Wing span size 6-12 feet, max. 22 ft)

Choose another fish Category

1. Disks and Ovals / Colorful

The first category of disk and oval shaped fish are very important to learn. They are colorful, large and very obvious and the three main families that make up the group can be found on almost every dive.

2. Silvery Fish

Silvery fish have many different family members, though we will look at just a few representatives. As opposed to the colorful butterfly, angel and surgeonfish, the silvery fish tend to blend in better in open water and are usually not found near the colorful bottom.

3. Sloping Head / Tapered Body

This third group of “fish-like” fish, are very important to learn. The are common on most dives and are also highly sought after as food fish. It is especially important to monitor these fish to provide data for fisheries management. Snappers can be very difficult to tell apart from the similarly shaped grunts. One helpful hint is to look at their tails. Snappers tend to have straight, flat tails. They are also known for their habit of snapping their mouth open and shut when caught on hook and line. They have very sharp canine teeth that can provide a nasty bite to the unsuspecting angler. Look closely on your next dive and you may see the small teeth protruding from the side of the mouth. Grunts on the other hand, have slightly notched tails. They get their name from the grunting sounds they emit when threatened. These sounds are created by rubbing together bony teeth plates located in the back of the throat. Since the teeth are in the throat, a diver will never see protruding teeth on a grunt, only big blubbery fish lips.

4. Small Ovals / Damselfish

While divers tend to first notice the larger, more obvious fish on a dive, after a short while the challenge to find new species leads them to change their search image to look for smaller, previously unnoticed fish. Generally, the first new species a diver will encounter will belong to the small oval shaped group. This group is broken into the damselfish and their close cousins the chromis. Damsels are like the surgeonfish in that they eat algae. They do not roam around grazing, but rather tend to small algae gardens like a farmer. These areas are guarded fiercely as the algae farm is the damsels food source. For that reason you can think of the damselfish as not just territorial, but Dam- selfish with its territory. Many damselfish have distinctly different colors as juveniles, often being much brighter and more colorful when they are young and becoming drab with age. (much like us humans!) For this reason, the juveniles have been heavily collected for the aquarium trade and are under heavy fishing pressure. As part of the REEF Fish Survey Project, divers are asked to monitor the juveniles and adults separately in two of the damselfish species – the Cortez damselfish and the giant damselfish.

5. Heavy Body / Large Lips

Heavy bodied, large lipped fish belong to the seabass family. We tend to refer to the larger seabasses as groupers and the smaller seabasses as bass or basslets. These fish are extremely important food fish and are under increasing threats from heavy fishing pressures. Monitoring these fish can help provide valuable data to aid in their protection. Most seabasses are hermaphrodites, meaning the same fish will be both a male and a female during its lifetime. The groupers are all born female and later change sex to become male. Most large groupers also congregate each year to spawn at a specific location, making them easy targets for emerging positioning and fishing technology.

6. Swim with Pectorals / Obvious Scales

The fish in this group all use their pectoral fins to swim with rather than the traditional tail swimming of most other fish. The scales are also quite large and obvious. These fish can also be hermaphrodites, like the groupers, with some fish changing sex and others staying the same. Intermediate and adult fish often have very different appearances compared to the always-male terminal phase. This means learning two colors to be able to ID the same species of fish. Most of the pictures shown in this curriculum are terminal phase males, unless noted.

7. Redish / Big Eyes

This group of reddish fish is normally not seen during day dives due to their nocturnal nature. The reddish color helps them blend in at night and the large eyes help them to see better.

8. Small, Elongated Bottom Dwellers

The small bottom dwelling fish often make up the most interesting fish to watch during your dive. Their approachable nature and interesting behaviors make them great fishwatching finds. Blennies tend to be slightly larger than gobies, but are most easily recognized by their curved body posture and expressive faces. Gobies, though similar in their habitat requirements, tend to sit flat and straight on the bottom. The jawfishes actually live in a burrow in the sand that they excavate and maintain.

9. Odd-Shaped Bottom-Dwellers

This category of fish is made up of families and species that didn’t quite fit anywhere else due to their unique body shapes.

10. Odd-Shaped Swimmers

This group of fish contain families that are unusual in their shape, but are swimmers rather than bottom dwellers.

11. Eels

Though looking like snakes, eels are fish. There are several different types of eels, and we will look at two – garden eels that live in burrows in the sand and moray eels. Moray eels have a bad reputation mainly due to the constant opening and closing of their sharp toothed mouths. However, this is not a threat to divers, as this action pumps water through their gills. Most eels are actually very shy.

12. Sharks & Rays

Even though the sharks and rays are cartilaginous (their skeletons are made of cartilage instead of bones), they are still referred to as fish and count during our surveys.

5 Fun Facts - Bull sharks & Whitetip reefsharks

Here in Costa Rica there are three shark species that you will encounter depending on the dive site and time of the year you dive. On our local dive sites we find white-tip reef sharks, nursesharks and of course the famous bullsharks at Bat Islands. Here are some fun facts about these majestic legends of the Costa Rican underwater world.

Bull Sharks: Masters of Estuarine Environments: Bull sharks frequently inhabit estuarine environments, where freshwater from rivers meets saltwater from the ocean. Their ability to navigate and adapt to these fluctuating salinity levels showcases their resilience in diverse ecosystems.

Bull Sharks' Unique Reproductive Strategy: Bull sharks have a fascinating reproductive strategy known as "placental viviparity." This means that the embryos develop inside the mother, receiving nutrients from a placental connection. This adaptation allows bull sharks to give birth to live pups rather than laying eggs.

White Tip Reef Sharks' Siesta Time: White tip reef sharks are notorious for their docile demeanor during the day. Often found resting in caves or under coral ledges, they seem to have a daily siesta, allowing divers to observe their more relaxed side before they become more active during nighttime hunting expeditions.

White Tip Reef Sharks' Tandem Hunting: White tip reef sharks are known for their cooperative hunting behavior. They often hunt in groups, using a method known as "tandem swimming" to corral schools of fish into confined spaces, making it easier for them to catch their prey. On rare occasions this behavior can be observed at the Catalinas Islands on the South Point dive site.

White Tip Reef Sharks' Intricate Courtship Rituals: White tip reef sharks engage in elaborate courtship rituals that involve swimming together and nuzzling each other. These displays are not only fascinating to witness but also play a crucial role in the bonding process between potential mates.

5 Fun Facts - Rays

Costa Rica is a paradise for those who love to see rays under water. Here on our local dive sites we find a wide variety of ray species. When you come diving with us there is a good change you might encounter any of the following rays: Pacific spotted eagle ray, round sting ray, electric ray, leopard round stingray, longtail stingray, golden cownose ray, southern banded guitarfish, bullseye electric ray, butterfly ray, Pacific chupare stingray, spiny tail round stingray, Mobula Rays and even the Giant Manta Rays at Catalinas or Bats Islands.

Stingrays' Hidden Talents: Several species of stingrays inhabit Costa Rican waters, with the most iconic being the southern stingray. These rays are masters of camouflage, burying themselves in the sandy ocean floor, only their eyes and spiracles (respiratory openings) exposed. Despite their name, stingrays are generally docile and only use their venomous tail spines for defense.

Mobula Madness: Costa Rica is a seasonal playground for mobula rays, also known as devil rays. These acrobatic swimmers are known for their incredible leaping displays, often soaring several feet above the water's surface. The reasons behind these breathtaking jumps are not entirely understood but are believed to be related to communication, courtship, or the removal of parasites.

Ray Nursery Grounds: The shallow coastal areas of Costa Rica, such as those around the Gulf of Papagayo and Playas del Coco, serve as essential nursery grounds for many ray species. These protected environments provide a safe haven for juvenile rays to grow and develop before venturing into deeper waters.

Eagle rays bottom feeders: actively search for prey on the seafloor. Similar to stingrays, their mouths are positioned on the underside of their bodies. Notably, they possess a distinctive protruding snout, employed at times to sift through the sand in search of delectable meals. Categorized as carnivores, eagle rays feature specialized flat teeth specifically crafted for grinding and crushing crustaceans and mollusks. Despite this specialization, their dietary preferences are not limited, as they readily consume a variety of fare including worms, small fish, and even octopuses. This adaptability in their feeding habits highlights the diverse range of food sources they exploit in their underwater environments.

Electric defence: Similar to its relatives, the ocellated electric ray (bullseye electric ray) has a defense mechanism in the form of a moderate electric shock. During daylight hours, this solitary ray predominantly rests partially buried in the sand, frequently in proximity to rocky reefs. Its nocturnal behavior sees increased activity, with the ray utilizing its pelvic fins to "hop" along the seabed. The ocellated electric ray sustains itself by consuming small crustaceans like amphipods and shrimp, along with polychaete worms.