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Captiva Island

Fun Fish Friday - The Seahorse

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Fun Fish Friday - The Seahorse

Now that the excitement of summer camp is over, we think it's time to reinstate Fun Fish Fridays. This week we are going to learn about a very unique fish that doesn’t look much like its cousins – the seahorse. That’s right, the seahorse is actually a highly modified fish in the class Actinopterygii, or ray-finned fishes. The seahorse belongs to the genus Hippocampus, which literally translates from Ancient Greek to “horse” (hippos) and “sea monster” (kampos). This horse-like fish is prevalent in the waters around Sanibel and Captiva; we actually have 3 species that inhabit the region: the dwarf seahorse, lined seahorse, and longsnout seahorse.

The dwarf seahorse (Hippocampus zosterae) is common in the seagrass beds in Florida and throughout the Caribbean. 

Let’s start with the basics. Seahorses have the same basic fins as most other fish: a dorsal fin and paired pectoral fins. However, instead of a caudal fin (tail fin) the seahorse has an elongated, prehensile tail that it uses for stabilizing itself in the ocean currents. It wraps its tail around seagrass or coral and hangs on tight, helping it save energy for other uses. We've even observed a seahorse catching a ride on an arrow crab's back!

Notice the curved prehensile tail of this lined seahorse (Hippocampus erectus). This species can grow up to be almost 6 inches!

Like many other fish, seahorses are voracious, carnivorous predators, but because they have no true stomachs, they have to constantly eat to meet their energy requirements. Some seahorses may consume up to 3,000 brine shrimp in one day!  To chow down on so many crustaceans, they have a specialized mouth. Their jaw is fused, creating a straw-like shape that enables them to ambush and quickly slurp up their prey.

One of the seahorse's favorite meals, the brine shrimp, is an aquatic crustacean that is only slightly related to true shrimp. 

There is one aspect of a seahorse’s life that differs quite drastically from other fish. When seahorses are ready to reproduce, the male and female engage in an elegant courtship dance to seal their bond. Soon after, the female deposits her eggs into the male’s brood pouch where they are fertilized and incubated for up to 25 days. The male will then give birth to hundreds or thousands (depending on the species) of baby seahorses that are miniature copies of the adults. Scientists aren’t exactly sure of the biological advantages of Mr. Mom, but one theory is that it could allow the female to begin producing eggs as soon as she delivers her last batch to the male. Check out the courtship dance of one of the seahorse's closest relatives, the Weedy Seadragon:

Because seahorses are so unique and sensitive to environmental changes, scientists are studying them to better understand how to improve the overall health of our oceans on a global level - find out more here: http://seahorse.fisheries.ubc.ca/why-seahorses

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5 Ways to protect sea turtles

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5 Ways to protect sea turtles

This week's post is by high school intern Adam Tardif, in collaboration with Nicole Finnicum. Thanks Adam!

Here on Sanibel, we all love our sea turtles, and we want to make sure that we are good neighbors to them. As the sea turtle nesting season begins, it is important to realize that humans can sometimes disturb the nesting process without even realizing it. Here are five things you can do as an individual to help in the effort to protect sea turtles:

1. Don't litter. Large pieces of litter can act as a physical barrier to sea turtles searching for the perfect nesting site. Also, trash floating in the ocean (plastic bags, Styrofoam, plastic bottles, fishing lures, etc.) can resemble common sea turtle food items, and if ingested can cause turtles to choke or experience digestive disturbances – not much fun for these magnificent creatures. But perhaps the best reason not to litter is that you will feel good knowing that you have helped to make Sanibel a safer place for wildlife.

Plastic bags floating in the ocean may resemble jellyfish, a common prey item for leatherback sea turtles. To help solve this problem, opt for reusable bags when you shop.

Plastic bags floating in the ocean may resemble jellyfish, a common prey item for leatherback sea turtles. To help solve this problem, opt for reusable bags when you shop.

2. Turn your lights off at night (especially if you live on the beach). Artificial lights can be distracting to adult sea turtles that are nesting – they have the most nesting success in just the light of the moon. Also, hatchling turtles will crawl towards the brightest light they see, which is usually the moon reflecting off of the ocean. Artificial light can be very confusing to a newly hatched turtle and may expose them to predation or cause them to become disoriented or lost.

3. Dispose of fishing materials in designated bins. Sea turtles are good swimmers and their front fins are very powerful. However, since sea turtles move their front fins in a circular motion, they frequently become entangled in fishing lines and ropes. Sanibel Sea School has placed monofilament recycling bins near popular fishing spots on Sanibel – please look for them and use them when you are fishing!

A sea turtle is found entangled in a buoy line...

A sea turtle is found entangled in a buoy line...

... is freed by a fisherman ....

... is freed by a fisherman ....

... and swims safely back into the ocean.

... and swims safely back into the ocean.

4. Leave the beach as you found it. We love spending a day at the beach, lounging in a beach chair and digging sand castles. But, sea turtles are clumsy on land and obstacles like beach furniture and holes are difficult for them to maneuver around, and could block them from reaching an ideal nesting site.

 

5. Don't drive on the beach. While driving on the beach can be lots of fun, vehicles pose a threat to nesting adults, and tire tracks in the sand can make traveling to the ocean much more difficult for recently-emerged hatchlings. While we are on the topic of transportation – watch out for sea turtles in your boat as well!

If you are interested in the most up-to-date information on local nesting sites on Sanibel and Captiva, click here

 

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What comes out of those mermaid’s purses?

About a month ago, one of our students found a mermaid’s purse in the Captiva seagrass beds. We often find these egg cases washed up in the wrack line and are sometimes lucky enough to see a tiny creature wiggling around inside. We usually toss them back into the ocean, but this time, we decided to bring it back to our tanks to see if we could find out what exactly would hatch.

We know that some sharks and skates house their eggs in mermaid’s purses, but we weren’t exactly sure which species we had on our hands. Skates are related to sharks and rays, and look very similar to the latter; they have a cartilage skeleton, flattened body, and enlarged pectoral fins. Unlike rays, however, skates lay their eggs in a small pouch made of collagen proteins that protect the developing embryo for up to 12 weeks. During this time, the skate will grow into a fully developed and independent juvenile, ready to take on the ocean.

Here is a  mermaid's purse, or skate egg case. Sometimes if you hold it up to the sun, you can see the baby skate wiggling around inside. If the skate has already hatched, then you will see an opening at one end between the two "horns". 

Here is a  mermaid's purse, or skate egg case. Sometimes if you hold it up to the sun, you can see the baby skate wiggling around inside. If the skate has already hatched, then you will see an opening at one end between the two "horns". 

After about a month in our seagrass tank, we saw no changes, but we were still hopeful that we would have a newborn skate soon. To our surprise, this past weekend our patience finally paid off - we came in Saturday morning and discovered a baby skate on the bottom of the tank! Hatching at a length of 5” and almost double the size of her egg case, this was no tiny baby! We determined that the species of our hatchling was a Clearnose Skate, due to the transparent skin on her nose, a common trait of this species. We plan to keep our baby skate in the safety of our seagrass tank for a couple of weeks, then we will release her back into the ocean so that she can live a happy and healthy life in the Gulf of Mexico. 

What look like eyes on the ventral (belly side) of the skate are actually nostrils. You can also see how the snout is semi-transparent, indicating that this is a clearnose skate.

What look like eyes on the ventral (belly side) of the skate are actually nostrils. You can also see how the snout is semi-transparent, indicating that this is a clearnose skate.

Clearnose skates can be found from Massachusetts all the way to southern Florida! They enjoy life on the soft, sandy seafloor and eat mostly crustaceans, bivalves, and squid. 

Clearnose skates can be found from Massachusetts all the way to southern Florida! They enjoy life on the soft, sandy seafloor and eat mostly crustaceans, bivalves, and squid. 

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