Florida has a great variety of turtles. Actually, the species richness here is higher than any other state – though Alabama may argue. Many are familiar to us. If we have not seen them, we have at least heard of them. But that may not be the case with map turtles.
Map turtles are in the same family as many of the common ponds turtles but are in the genus Graptemys. The patterns on their shells and skin are beautiful and they have raised scutes along the midline of their shells giving them a “sawback” or “dinosaur” look. They are associated with alluvial rivers due to their diet of shellfish, which cannot be found in the low pH waters of tannic rivers. To our west, in Alabama and Mississippi, there are several species of them. And as you move up into the Mississippi valley and into the Midwest, there are even more. But here in Florida there are only two. Let’s meet them.
The Barbour’s Map Turtle (Graptemys barbouri) is associated with the Apalachicola River system. First discovered in the Chipola River, it has now been found in the Chattahoochee, Flint, and Apalachicola River systems, as well as the Choctawhatchee and Pea Rivers. It may have been introduced to the Ochlockonee and Wacissa.
Barbour’s Map Turtle.
Photo: Rome Etheridge
Female map turtles are much larger than the males, and the female Barbour’s Map is the largest of all map turtles – with a carapace length of 33cm (13 in.). She has a very broad head (8cm, 3in. wide) to crush the shells of her favorite prey – snails. The males only reach 13cm (5in.) carapace length and their heads are much narrower. Barbour’s Maps prefer flowing rivers with limestone outcrops. These outcrops support the snails they like to eat. That said, they have been found in high numbers within the silty channels of these rivers.
Females take many years to mature, possibly as long as 14. Males mature in 3-4 years. Breeding begins in the spring and nesting begins in late April but will continue into August. Like most turtles, they seek out sandy beaches where they will lay multiple clutches of 7-10 eggs over the span of the nesting season.
Fallen trees (snags) are important basking areas and map turtles use them frequently. During the cooler months, and low water periods along the river, they will hide in deep pockets within the limestone rock. Their home range along the rivers are between 250 and 1500 meters (74 and 441 feet), with males having a larger range. Other than nesting, activity on land is not common.
Their populations seem to be stable, though they are protected by FWC and possession without a permit is illegal. Harvest does still happen, and the activity known as “plinking” (shooting them off their basking logs) occurs as well. Nest depredation, and the killing of adults, by raccoons is common. Crows are another threat.
The Escambia Map Turtle (Graptemys ernsti) is associated with the Escambia River. With the Florida section of this river only being 54 miles long, it has the most restricted range of any turtle in the state. That said, along these stretches of river, it is one of the more abundant turtles. Paddling a lower section of the Escambia I counted an average of 11 individuals per basking log. It has been found in the Yellow and Shoal Rivers as well. But due to the lower pH and lack of mollusks, they are not found in the nearby Blackwater and Perdido Rivers.
The Escambia Map Turtle is only found in the Escambia, Yellow, and Shoal Rivers.
Photo: Molly O’Connor
Like all map turtles, it has beautiful markings on the shell and head. Like all map turtles, it has the characteristic “sawback” appearance down the middle of the carapace. Like all map turtles, the females are much larger than the males. However, the female of this species is not as large as the female Barbour’s Map – with a carapace length of 28cm (11in.).
The males of this species feed on a variety of insects but the females stay with the characteristic molluscan diet. The introduced Asiatic clam (Corbicula fluminea) is a particular favorite. Breeding occurs in the spring and nesting area are sandbars found along the river’s edge. These turtles are having problems with ATVs using such nesting areas, the removal of snag basking trees, and plinking. There are also concerns with the building of dams along the Alabama portion of the river. They are protected by FWC, and you cannot possess them without a permit.
With only two species of map turtles in the entire state, and both only found in the panhandle, these are unique species to the rich variety of turtles found here.
As I write this, we are in the middle of our 2023 Scallop Search, an event we do each year to assess whether the scallops in Pensacola Bay are trying to make a comeback on their own. Each year I am amazed at how popular this little mollusk is. On the day I am writing, I will be working with a marine science class from the University of Southern Mississippi driving over from Ocean Springs. This past weekend I worked with two families who trailered their boat from Enterprise Alabama to participate. Those on the eastern end of the panhandle are well aware of the popularity of this creature. Folks from all over the southeast travel there to go scalloping. Many of the locals in my area, when I am training them how to do a scallop search, tell me that they head east and go scalloping every year. Some even have condos for that week and it is a large part of their annual vacation plans. And many of the locals here would love to see them return to Pensacola Bay.
This is a creature that draws a lot of attention. But most know very little about it. They know it has small eyes and can swim – actually… I have recently found that not everyone knows they can swim. We know they like grassbeds and they can be harvested in the summer. They may have done this long enough to know the prime spots within the grassbeds to search for them – their “sweet spots”. But not much more.
So… let’s meet the bay scallop.
Volunteers conducting the great scallop search.
Photo: Molly O’Connor
Its scientific name is Argopecten irradians. It is a mollusk in the class Bivalvia and the family Pectinidae. There are numerous species, and the group is found all over the world. The greatest variety of them are from the Indo-Pacific region, and in each case, they are a popular seafood. Most can swim, though erratically – they are not Michael Phelps – and they use this ability to avoid predators such as starfish, which they can see with the set of simple eyes.
There are five subspecies of A. irradians. A. irradians irradians, known as the bay scallop, or Atlantic Bay scallop (and from here is just “the scallop”) is our local variety. It is found from Cape Cod to the Gulf of Mexico. They begin life as a microscopic egg produced during the mass spawning of the hermaphroditic parents (hermaphroditic meaning each parent can produce sperm and egg). The timing of the release of gametes is triggered by warming water and usually occurs in the late summer/early fall. This early egg stage sinks to the bottom where it remains for a few weeks before hatching.
The hatched larva remain microscopic, are transparent, resemble the parents, and are called spat. The spat become part of the plankton in local estuaries but eventually return to the grass in what is called “spatfall” where they attached to the seagrasses using byssal threads. They continue to grow, eventually release from the grass, and become the scallops we all know and love. Many species of scallops can live over 20 years, but our local one only lives for one.
As most know, adult scallops have two shells (bivalves) connected at the hinge on the dorsal side of the animal. Though they do add weight to the shell, a disadvantage for a swimmer, the “ribs” provide a sturdier shell. The two shells are connected by a single, large adductor muscle, which is used to open and close the valves during swimming. It is this adductor muscle we eat when consuming scallops.
Like all bivalves, scallops are filter feeders but unlike most bivalves they lack siphons to draw water in and out of the digestive tract. Rather they lie with their valves slightly gaped and allow water to pass over them. Plankton is collected by a mucous layer and then moved to the gut by cilia (small hair-like structures) where it is digested.
Bay Scallop.
Photo: FWC
Like all bivalves, scallops lack a brain as we know it but rather function using a series of ganglia (groups of nerve cells) connected to a nerve ring. These ganglia can control movement of the muscle, gills, eyes, and are connected to a statocyst, which tells the scallop how it is oriented in the water column.
There are numerous eyes aligned along the edge of each valve that can detect movement and shadows. It is believed that they use their eyes to detect potential predators and possibly initiate the swimming behavior they are famous for.
Living only one year, and reaching maximum size in late summer during spawning, scallop harvesting is regulated to that time of year in Florida. Once common from Pensacola to Miami, they are now only found in large numbers in the Big Bend region. Due to the loss of scallops in other areas, many visit the Big Bend each year to go scalloping, putting heavy harvest pressure on those stocks. There have been efforts to try and enhance the existing populations as well as restore historic ones. Here in Pensacola Bay, Florida Sea Grant works with volunteers to monitor the water quality and seagrasses, as well as assess how the few existing scallops are doing.
For more information on panhandle scallops, contact your local Sea Grant Agent at the county extension office.
Everyone has noticed the intense weather that crossed the United States in recent years. Tornadoes are hitting communities throughout the Midwest, but are also hitting places like Seattle, southern California, and even recently Pensacola Beach. Thunderstorms, though common, are occurring in waves. Typical summer days here in the panhandle include afternoon thunderstorms, but recently there have been daily squall lines beginning as early as 9:00am. I was recently camping out west and we encountered three hailstorms. Though these do occur out there, they were becoming a common thing and were also encountered in multiple states. And of course, there are hurricanes. Some are more intense and increase intensity as they come ashore, instead of decreasing as has been the rule over the decades.
This squall line formed early in the morning. One of many morning thunderstorms formed over a period of a week in the summer of July 2023.
Photo” Rick O’Connor
Many have pointed the finger at climate change as being part of the reason why these intense weather events are increasing, and climatologists have said for decades this could happen. To better understand what is driving these storms, I decided to grab one of my old college textbooks from the shelf and read what actually forms and fuels these weather events. The Nature of Violent Storms was published in 1961, and reprinted in 1981, by Dr. Louis Battan. Though many things that were unclear at the time of the writing have been discovered, the mechanisms that generate and fuel these storms were understood.
The mechanism that begins storms is convection cells within the air rising from the earth’s surface. The air moving over warm land or water warms as well and begins to rise. The rising air lowers the air pressure at the surface and is called a low pressure system. We associate low pressure systems with storms. These storms form due to unstable air masses in this rising column of air. The greater the temperature difference between the warmer air near the ground, and the cooler air in the upper atmosphere, the more unstable the air becomes and the faster the column of air rises. As the air rises it begins to cool, become denser, and falls back to earth like a water fountain shooting water into the air. This is the convection cell we have heard about.
However, if the air mass holds a lot of moisture (humidity) the release of heat from this humid air mass rising in the column can warm the environmental air mass surrounding it enough to cause the rising air mass to continue higher into the atmosphere increasing its speed while doing so. We can see this as cumulus clouds building over the landscape and, if humid enough, you can literally watch the thunderhead build. If supplied with enough water vapor and heat, these thunderheads will grow all the way to the tropopause (the lower layer of the stratosphere where the atmosphere itself begins to warm, not cool) and form the “anvil” shape of a thunderhead we are all familiar with. As a college student taking coastal climatology (the class this book was associated with) we would sit outside of Dauphin Island Sea Lab at mid-afternoon and bet on which thunderhead would reach the tropopause first.
The upper layer of the lower atmosphere is quite cold. Here the releasing water vapor condenses into rain droplets, ice, and often hail. They fall back towards earth. Much of the ice and hail melt before reaching us but under intense conditions this frozen precipitation can reach the earth’s surface as hailstones, some being as large as three inches across. One storm we encountered in Colorado this year had hailstones about the size of a large marble. We heard that at a nearby amphitheater the hail reached the size of golf balls and many who were there to see a concert (and there was no cover to hide) were taken to the hospital.
A hail storm encountered by the author in Colorado.
Photo: Rick O’Connor
The one common denominator in the formation of such storms is the presence of a warm landmass or water body. The warmer these land masses and water bodies are, the more energy there is for the enhanced convection and severe storm formation. And these land masses, and water bodies are getting warmer.
Hail stones are formed from ice that manages to remain solid as precipitation in very unstable air masses. They can reach three inches across.
Photo: Rick O’Connor
What has changed is the atmosphere itself. There are gases within the atmosphere that allow solar rays to pass through reaching the surface of the earth, but do not allow the warmed air caused by the warming of land and sea from this solar radiation to escape back into space – the so called “greenhouse effect”. This is actually good; it keeps our planet at a warmer temperature than it would be if these gases were not present and allows life to exist here. However, an increase in these “greenhouse gases” can increase the overall temperature and create problems – intense storms being one of them. The surface of the planet Venus is around 900°F. Even though the planet Mercury is closer, Venus is warmer due to the heavy amount of greenhouse gases in its atmosphere. At temperatures like this, it is understandable that life does not exist there, and scientists do not believe it could. Getting scientific instruments to the surface of Venus is difficult due to the large amount of sulfuric acid in the clouds, much of this coming from intense volcanic activity there.
The greenhouse effect.
Image: NOAA
On Earth, our temperatures are climbing – slowly, but climbing. As the atmosphere warms due to the greenhouse effect, it increases the temperature of the land mass and water bodies. Increased temperatures in Pensacola Bay have triggered some die offs of oysters, and the warming Mobile Bay has increased the number of jubilee’s occurring there. Remember, high water temperatures mean low dissolved oxygen levels. Increased surface temperatures will create more unstable air masses and a breeding ground for the formation of vortices that can, and do, lead to more intense thunderstorms and tornadoes. Surface temperatures are increasing in locations where historically such weather events have not been common, like Seattle. Recently, I had to make a trip to a department store at one of our local malls. Leaving the house, as I crossed our wooden deck and walked through the yard to the truck, it was definitely warm – it was July. However, when I arrived at the store, where all was concrete and asphalt, the temperature difference was striking. It was MUCH warmer. Actually, at the store front it was almost unbearable. In many of our large cities, and even in smaller ones, we have converted much of the natural landscape to concrete and asphalt, which is increasing the surface temperatures even more, and enhancing unstable air even more. We have all heard that large cities create their own weather, and it is true.
So…
How do we turn this around?
I see two paths. (1) Reduce the source of the heating – greenhouse gases. (2) Mitigate the impacts of the heating.
There are several sources of greenhouse gases, and these have been discussed in other articles, but certainly the use of fossil fuels is a major one and reducing our dependency on these would be a good start. But we are moving very slowly on this, the will to do it just is not strong enough.
To mitigate the impacts, we would need to re-think how we grow and develop the landscape. Even today, many of the new subdivisions I see clear all of the vegetation, place the houses close together with little or no green space, use asphalt roofs, and replace little or none of the vegetation. It seems our development plan does not have the will to make some much needed changes in planning either. There are many ways in which we can develop our landscape to help mitigate the warming that is occurring. Many researchers at the University of Florida have been working on this for many years. For ideas and suggestions, just contact your county extension office.
Based on the 2021 Intergovernmental Panel on Climate Change’s report, we may be past the tipping on sea level rise, but we are not on other negative impacts of climate . It is understood that with any mitigation efforts right now, there will be a lag time of several years before things begin to turn around, it is not too late. We can do this.
When snorkeling the grassbeds of the Florida panhandle encountering a reptile has a low probability, but it is not zero. Of all the reptiles that call this part of the state home, few enter marine waters and most of those are very mobile, moving up and down the coast heading from one habitat to another. In fact, there are no marine reptiles that would be considered residents of our seagrasses, only transients.
The one species that you might encounter is the green sea turtle (Chelonia mydas). This is the largest of the “shelled” sea turtles and has a vegetarian diet. With a serrated lower jaw, they can be found grazing in the seagrass beds feeding on both the grasses and the species of algae found there. The carapace length of these large reptiles can reach four feet and they can weigh up to 400 pounds. Their coloration is similar to that of the loggerhead sea turtle (Caretta caretta) but their heads are smaller and there are only two large scutes between the eyes rather than the four found in the loggerheads. The colors of the skin and shell have shades of brown, yellow, orange, and some black and can be quite beautiful. The name “green” sea turtle comes from the color of their internal fatty tissue. Feeding on a diet of seagrasses, it becomes green in color, and this was discovered by early fishermen who hunted and consumed this species. It is the one used most often in what is called turtle soup and is actually farmed for this dish in other countries.
The green sea turtle.
Photo: Mile Sandler
Like all sea turtle species, they are born on the Gulf side of our barrier islands. If they successfully hatch, they work their way to the open water and spend their early years in the open sea. Some have been associated with the mats of Sargassum weed floating offshore, feeding on the variety of small invertebrates that live out there. They will also nip at the Sargassum itself. As juveniles they will move back into the coastal estuaries where they begin their vegetarian lifestyle. As adults they will switch time between the open sea and the grass filled bays. Once unfortunate side effect of feeding in our grassbeds is the frequency of boat strikes. There are tens of thousands of motored vessels speeding through our grassbeds and the turtles surfacing for air can be targets for them. Our hope is that more mariners are aware of this problem and will be more vigilant when recreating there.
Another turtle who IS a resident of the estuary is the much smaller diamondback terrapin. Though terrapins much prefer salt marshes they will enter seagrass beds, and some spend quite a bit of time there. Terrapins prefer to feed on shellfish so, moving through the grassbeds it is the snails and bivalves they seek. Because of their size they feed on the smaller mollusk. A typical terrapin will have a carapace length of about 10 inches and may weigh two pounds. They will take small crabs and shrimps when the opportunity is there, and they are known to swim into submerged crab traps seeking the bait. Unfortunately, being air breathing reptiles, they will drown after becoming entrapped. It is now required that all recreational crab traps in Florida have bycatch reduction devices (BRDs) on each of the funnel openings to reduce this problem. Many studies, both here in Florida and elsewhere, have shown these BRDs do not significantly reduce crab catch and so you can still enjoy crabbing – just not while catching terrapins. Encountering one snorkeling would be a very rare event, but – particularly in the eastern panhandle – has happened.
Diamondback terrapin.
Photo: Rick O’Connor
A third reptile that has been seen in our grassbeds is the American alligator (Alligator mississippiensis). Preferring freshwater systems, encounters with alligators in an open seagrass bed are rare, but do happen. There are plenty of freshwater ponds on some of our barrier islands that the alligators will use. They have been seen swimming out into the seagrass beds and often will cross the bay, or Intracoastal Waterway, to mainland side. They have also been seen swimming near shore in the Gulf of Mexico. Though they can tolerate saltwater, they have a low tolerance for it and do not spend much time there.
Alligators are top level carnivores feeding on a variety of wildlife. Like most predators, they tend to seek and capture the easiest prey. Most often these are fish, reptiles, or small mammals. But they will take on large birds or deer if the opportunity presents itself. Despite their natural fear of humans, they have taken pets and also have attacked humans.
Having only canines in their mouths, they must grab the prey and swallow it. Lacking molars, they cannot chew. So, more often than not, they select prey they can swallow whole. If they do grab a larger animal, they are known to drown the creature in what has been termed the “death role” and cache it beneath the water under a log (or some structure) where it will soften to a point where they can cut small pieces and swallow it. All of the alligators I have seen in our grassbeds were definitely heading somewhere. They were not spending time there. After heavy rains the salinity may drop enough to where they can tolerate being out there longer and encounters could increase. But they are still rare.
Alligator
Photo: Molly O’Connor
I will mention here that there are several species of snakes that, like the alligator, are swimming from one suitable habitat to another – crossing the seagrass in route. All snakes can swim and encounters in brackish water are not unheard of. I have several photos of diamondback rattlesnakes (Crotalus adamanteus) swimming across the Intracoastal Waterway between the mainland and the islands.
Eastern diamondback rattlesnake swimming in intracoastal waterway near Ft. McRee in Pensacola.
Photo: Sue Saffron
Encounters with reptiles are rare in our seagrass beds but pretty exciting when they do occur. There is certainly no need to fear swimming or snorkeling in our bay because they are so rare. But maybe one day you will be one of the lucky ones who does see one.
One of the community science volunteer projects I oversee in the Pensacola area is the Florida Horseshoe Crab Watch. The first objective of this project is to determine whether horseshoe cabs exist in your bay – FYI, they do exist in Pensacola Bay. The second objective is to determine where they are nesting – we have not found that yet, but we have one location that looks promising. One of the things my volunteers frequently find are the molts of the horseshoe crabs. Many keep them and I have quite a few in my office as well. One volunteer was particularly interested in the fact that they even molted and that they could leave this amazing empty shell behind and yet still be crawling around out there. So, I decided to write an article explaining the process in a little more depth than I typically do.
Horseshoe crab molts found on the beach near Big Sabine.
Photo: Holly Forrester.
I titled the article “The Molting of Crabs” but it could be the molting of any member of the Phylum Arthropoda – they all do this. The Phylum Arthropoda is the largest, most diverse, and successful group of animals on the planet. There are at least 750,000 species of them. This is three times the number of all other animal species combined. One thing unique to this group is the presence of an exoskeleton.
The exoskeleton is made of chiton and is secreted by the animal’s hypodermis in two layers. It provides the protection that the calcium carbonate shells of mollusk do but is much lighter in weight and allows for much more movement. Arthropods have jointed legs, hence their name “arthropod – jointed foot”, to enhance this movement even more. The entire body is covered by this exoskeleton.
The outer layer is thin and called the epicuticle. It is composed of proteins and, in many arthropods, wax. The inner layer is the thicker procuticle. The procuticle consists of an outer exocuticle and an inner endocuticle. These are composed of chiton and protein bound to form a complex glycoprotein. The exocuticle is absent at joints in the legs and along lines where the shell will rupture during molting. In the marine arthropods the procuticle includes salts and minerals. Where the epicuticle is not waxy and is thin, gases and water can pass into the animal’s body. The cuticle also has small pores that allow the release of compounds produced by glands within the animal. Not all of the cuticle is produced on the outside of the body. Some portions of it are produced around internal organs.
The colors of the crabs and other arthropods are produced by concentrations of brown, yellow, orange, and red melanin pigments within the cuticle. Iridescent greens, purples, and other colors are produced by striations of the epicuticle refracting light.
One disadvantage of the protective exoskeleton is the fact that it does not grow as fast as the interior soft tissue. They have solved this problem by periodic shedding, or molting, of the shell. Science calls this ecdysis, but we will continue to call it “molting”.
Step one is the detachment of the hypodermis from the skeleton. The hypodermis now secretes a new epicuticle. Step two, the hypodermis releases enzymes which pass through the new epicuticle and begin to erode the untanned endocuticle of the old skeleton. During this process the muscles and nerves are not affected and the animal can continue to move and feed. Step three, the old endocuticle is now completely digested. With the new procuticle produced by the hypodermis, the animal is now encased by both the old and new skeleton. Step four, the old skeleton now splits along predetermined lines, and the animal pulls out of the old skeleton. The new exoskeleton is soft – hence, the “soft-shelled blue crab” – and can be stretched to cover the increased size of the new animal. This stretching occurs due to tissue growth during steps 1-3, and from the uptake of air and water. The hardening of the new skeleton occurs due to the tanning of the new cuticle.
Stages between molts become longer as the animal grows older. Thus, there are numerous molts when the animal is young and as they age, they become fewer and farther between. Most insects have a finite number of molts they will go through. The marine arthropods seem to molt throughout their lives, though some species of crabs cease molting once they reach sexual maturity.
Molting is under hormonal control. Ecdyisone is secreted by certain endocrine glands, circulated through the blood stream, and acts directly on the epidermal cells. There are hormones that, if secreted, will inhibit the molting process. These are usually released if the animal senses trouble and that is not a good time.
During the period when the old shell is being digested many of the salts and minerals are absorbed by the tissue of the animal. Some people can eat crab but have allergic reactions when consuming soft shell crabs – most likely due to the increased salts and minerals in the tissue at this time. During step 3, many crustaceans will seek shelter and will remain there for a period of time after molting allowing the new shell to harden. The regeneration of lost limbs occurs during the molting process as well.
Molts of many species are hard to find because the “soft-shelled” animal can consume the molt to increase needed salts and minerals – or other marine animals may do so for the same reason. But horseshoe crab molts are pretty common and cool to collect. Another common molt found is that of the cicadids in the pine forest areas of our panhandle. The entire process is pretty amazing.
Reference
Barnes, R.D. 1980. Invertebrate Zoology. Saunders College Publishing. Philadelphia PA. pp. 1089.
