by Rick O'Connor | May 27, 2020
As we continue our series on marine life in the Gulf of Mexico, we also continue our articles on marine worms. Worms are not the most charismatic creatures in the Gulf, but they are very common and play a large role on how life functions in this environment. Roundworms are VERY common. There are at least three phyla of them but here we will focus on one – the nematodes.
A common nematode.
Photo: University of Florida
Most nematodes are microscopic, a large one would be about 2 inches, and some beach samples have found as many as 2 million worms in 10 ft2 of sand. So, what do we know about them? What role, or function, do they play in the ecology of the Gulf of Mexico?
Well first, they are long and round – cylinder shaped. There is a head end, but it is hard to tell which end is the head. Round is considered a step up from being flat in that it can allow for an internal body cavity. An internal body cavity can allow for the development of internal body organs. Internal body organs can move large amounts of nutrients, blood, oxygen, and hormones around the body allowing the animal to become larger. Some argue that a larger body can have advantages over smaller ones. Some say the opposite, but either way – a large body has been successful for some creatures and an internal body cavity is needed for this.
That said, the nematodes do not have a complete internal body cavity. So, they do not have a complete assortment of internal organs. Being round reduces your efficiency in absorbing enough needed nutrients, oxygen, etc. through your skin alone and this MAY be a reason they are small. They are very small.
There are free living and parasitic forms in this group. There are at least 10,000 species of them, and they can be found not only in the marine environment, but also in freshwater and in the soil found on land. They have played a role in the success of agriculture, infesting both crops and livestock. Nematodes can be a big concern for farmers and gardeners.
The free-living forms are known to be carnivorous, feeding on smaller microscopic creatures. They have toothed lips, and some have a sharp stylet to grab or stab their prey. Some stylets are hollow and can “suck” their prey in. Moving through the environment, they can consume algae, fungi, and diatoms. Some are deposit feeders and others are decomposers. On our farms and in our gardens, they are known to enter plants via the roots and can be found in the fruit.
The life cycle of the human hookworm.
Image: CDC
The parasitic version of nematodes has been a problem for some species. In humans we have the hookworms and pinworms. Dogs have their heart worms. An interesting twist on the parasitic nematode way of life, compared to flatworms like tapeworms, is their lack of a secondary (or intermediate host). The entire life cycle can take place in the same animal.
Females are larger than males and fertilizations is internal. Males are usually “hooked” at the tail end and hold on to the females during mating. About 50 eggs will be produced and released into the digestive tract, where they exit the animal in the feces and find new hosts either by the feces being consumed or drifting in the water column.
There multiple forms of parasitism in nematodes.
– Some are ectoparasites (outside of the body) on plants.
– Some are endoparasites in plants – some forming galls on the leaves.
– Some infest animals but only as juveniles.
– Some live-in plants as juveniles and animals as adults.
– Some live-in animals as juveniles and plants as adults.
It would be fair to say that many forms of marine creatures have nematodes living either within them, or on them. Some can be problematic and cause disease; some diseases can be quite serious. Others play an important role in “cleaning” the ocean, filtering the sand of organic debris. Many have heard of nematodes but know little about them. Either good or bad, they do play roles in the ecology of the Gulf of Mexico. 
by Rick O'Connor | May 17, 2020
In my time educating the public about Florida turtles I have found that most Floridians have not heard of diamondback terrapins. They have heard of, and seen turtles, but are not sure what the names of the different species are and are not familiar with the term terrapin at all. Which brings up the question – what is the different between a turtle, a tortoise, and a terrapin?
The light colored skin and dark markings are pretty unique to the terrapin.
Photo: Molly O’Connor
Honestly, they are cultural terms and not “biological” descriptions. We associate the term “tortoise” with a land turtle – and this is true – yet we call the box turtle a “turtle” – which is fine. In Great Britain they call almost everything a “terrapin”. The term “terrapin” is a Delaware Indian term meaning “edible turtle”. Most turtles are edible, but this term stuck to a group of brackish water turtles in the Chesapeake area near Delaware we now call “terrapins”.
In the Mid-Atlantic states, terrapins are more known than they are here – and they appear to be more abundant. They are the mascot of the University of Maryland, and the official state reptile there. “Turtle Soup”, a popular cultural dish in the Chesapeake, is made with terrapins. It was served as part of the state dinner when Abraham Lincoln was president – considering it a classic “American” dish. They were harvested by walking through the marshes with a burlap sack and a gig. A sack could bring a harvester about $10, but when the popularity of the dish increased, hand harvesting could not keep up with demand and terrapin farms began. I know there were terrapin farms in the Carolinas, but there was one near Mobile, Alabama as well. Apparently, terrapins existed outside of the Chesapeake – and that brings us back to Florida… we have them too!
Ornate Diamondback Terrapins Depend on Coastal Marshes and Sea Grass Habitats
There are seven subspecies of this brackish water turtle. They range from Massachusetts to Texas. It is the only resident brackish water species, spending its whole life in salt marshes (or mangroves in south Florida). Florida has five of the seven subspecies, and three of the seven ONLY live in Florida – yet most of us do not know the animal exist.
Very few researchers worked with terrapins in this state – there was virtually nothing known about them in panhandle. In 2005 I began to survey panhandle marshes to see if terrapins existed here. I grew up in the panhandle, and like so many others, had never seen or heard of one. I asked local fishermen who use to gillnet the marshes back in the 1950s and 1960s (when it was allowed) if they were aware of this this turtle. I asked them “did you ever capture a terrapin?” They did not know what I was talking about. And then I showed them a picture… “OH… yea, we did catch these once in a while – what are they called again? Terrapins?”. This was a game changer for me in terrapin education – show them a terrapin and ask if they have ever seen a turtle that looks like this.
The response was still “what is that? It’s beautiful!”… and they are. Terrapins have light colored skin with dark specks or bars – a really pretty cool looking turtle. Oh, and they are in the panhandle, just not in big numbers – or, at least, we have not found them in big numbers 😊.
These brackish water turtles spend their entire lives in a marsh system feeding on mollusk and crustaceans. Like map turtles (their nearest cousins), the females are larger with wide heads for crushing the shells of their prey. They are considered an important member of the ecosystem in that the reduction of terrapins can cause an increase in the marsh periwinkle (a popular snail food) who would in turn stop feeding on leaf litter and attack the live plants themselves – threatening the existence of the marsh. So, they are important predators on marsh grazers. Not having a lot of trees in a salt marsh, you do not see them basking on logs as you do with other riverine turtles. They do, however, exit the water and bury in the mud/sand for long periods to bask.
A baby terrapin.
Photo: Molly O’Connor
After mating, the females usually leave the marsh for the open estuary, swim along the shorelines looking for high/dry ground for nesting. More often than not, these are sandy beaches – but they have been known to dig nest in crushed shell mounds, dredge spoil islands, along highways, backyards, and even runways of airports – wherever “high and dry” can be found in a marsh. In Louisiana a lady found one roaming around inside her outdoor shower – good luck nesting there!
The females lay about 10 eggs in a clutch and will lay more than one clutch each year. Baby terrapins are one of the coolest looking turtles you will see. They emerge from the nest in late summer and fall, hiding in the wrack debris along the shoreline. It is believed they actually have a more terrestrial life early on before entering the water and living out their lives in the marsh.
The popularity of turtle soup has waned since the Civil War, as have the wild harvest and aquaculture projects. However, the turtle is still under tremendous pressure from humans. We began using wired crab traps in the 1950s and terrapins have a habit of swimming into these, where they drown. The problem is not that large in Florida, but in the Chesapeake, they have found as many as 40 terrapins in one crab trap! Most of these are “ghost crab traps” – ones that “got away” from the owner but are still harvesting marine live – including crabs. One paper indicated that in the early part of the 21st century, in one year in the Chesapeake, over 900,000 blue crabs died in ghost crab traps – a commercial value of about $300,000. So, the ghost crab trap is a problem whether it kills terrapins, redfish, flounder, or blue crab. Today, many crab traps have biodegradable panels so that if the trap “gets away” it will eventually breakdown and not capture organisms like terrapins. In the Chesapeake many states require crab traps to have a By-Catch Reduction Device (BRD) to keep terrapins out – but allow crabs in. They are not required in Florida, however FWC will provide them for free if you are interested. I have some in my office in Pensacola and more than willing to give them to you. FWC also hosts crab trap removal programs, and I encourage you to participate in these.
This orange plastic rectangle is a Bycatch Reduction Device (BRD) used to keep terrapins out of crab traps – but not crabs.
Photo: Rick O’Connor
A bigger issue for Florida is the land-based predators. As we moved closer and closer to the salt marshes, we built bridges and roads that allowed land-based predators to reach the nesting beaches they previously did not have access to. Raccoons in particular are a big problem, depredating as many as 90% of the terrapin nests. Poaching for the pet trade is rising and FWC is working on this. Several major arrests have been made in Florida in recent years. It is illegal to sell Florida turtles, so do not buy them if you see them being sold somewhere. Report the activity to FWC.
Due to all of this, terrapins afford some form of protection in each of the coastal states where they exist. Some list them as “endangered” or “threatened”. In Florida, they do not have this label, but they are protected by FWC. No one is allowed to have more than two in their possession, and you are not allowed to have any eggs.
It is an amazing turtle. I currently conduct a citizen science program monitoring them in the western panhandle. I have a lot of eager volunteers wanting to see their first one in the wild. I hope they do soon. I hope they hang around long enough for everyone to see one in the wild.
by Rick O'Connor | May 14, 2020
As we embrace the marine life of the Gulf of Mexico during this year of “Embracing the Gulf”, we are currently hooked on worms. In the last article we talked about the gross and creepy flatworms. Gross because they are flat, pale in color, only have a mouth so they have to go to the bathroom using it – and creepy in that many of them are parasites, living in the bodies over vertebrates (particularly fish) and that is just creepy. You may ask why would we even “embrace” such a thing? Well… because they do exist and most of us know nothing about them.
A nemertean worm.
Photo: Okinawa Institute of Science
This week we continue with worms. We continue with a different kind of flatworm. They are not as gross, but maybe a little creepy. They are called nemertean worms and I am pretty sure (a) you have never heard of them, and (b) you have never seen one. So why “embrace” these? Well… again it is education. They do exist, and one day you MAY see one – and know what you are looking at.
Nemerteans are flatworms. They are usually pale in color but a different from the classis fluke or tapeworm in a couple of ways.
1) They do have a way for food to enter and another for waste to leave, what we call a complete digestive tract – and that’s nice.
2) They have this long extension connected to their head called a proboscis. Many of them have a dart at the end they can use to kill their prey – and that’s creepy.
3) And as mentioned, most are carnivores, feeding on small invertebrates – and that’s okay.
We rarely see them because they are nocturnal – hiding under rocks, shells, seaweed during the day and hunting at night. Most are about eight inches long but some in the Pacific reach almost eight feet!
I would put that in the creepy file.
As we said, they are usually pale in color, though some may have yellow, orange, red, or even green hues to them. Their heads are spade shaped and, again, hold a retracted proboscis. This proboscis can be over half the length of the worm. At the end is a stylet (a dart) which they can use to stab their prey (small invertebrates). They can stab repeatedly, like using a knife, – they may stab and grab, like using a claw – or they may be a species that has toxin and kills their prey that way.
Nice.
Some would add this to the creepy file as well. A long pale worm, moving at night, extending a long proboscis when they get near you with a sharp dart at the end they essentially “sting” you like a bee.
Yea, creepy.
But we NEVER hear about such things with humans. They hunt small invertebrates like amphipods, isopods, and things like that. If you picked one up, would it stick the dart in you? My hunch would be yes – I honestly don’t know, I have only seen one to two in the 35+ years I have been teaching marine science and I did not pick them up. I have never met anyone who has and have never read “DON’T PICK THESE UP – VERY DANGERSOUS”. So, my hunch is that it would not be very painful at all.
But don’t take my word for it – again, I have rarely seen one… so, don’t pick them up 😊
There are about 650 species of nemertean worms in the world, 22 live in the Gulf of Mexico, and 16 live in the northern Gulf (near us). They are basically marine, move across the environment on their slime trails, seeking prey primarily by the sense of smell at night. Unlike the flukes and tapeworms, there are male and females in this group. They fertilize their eggs externally to make the next generation of these harpooning hunters of the Gulf.
I don’t know if you will ever come across one of these. You will know it by the flat body, pale color, and spade-shaped head, but I think it would be pretty neat to find one. There are more worms to learn about in the Gulf of Mexico, but we will do that in another edition.
by Rick O'Connor | May 3, 2020
Map turtles (Graptemys) are pretty common across much of the eastern and midwest areas of the United States. Not so much in Florida. There are only two species, and they are only found in the panhandle. However, the range for those two species is mostly in Florida making them a unique Florida turtle, and ones that both the state and federal agencies monitor for occurrence.
The Barbour’s Map Turtle sitting on a tree stump in the Chiploa River.
Photo: Molly O’Connor
In the 1940s and 50s it was believed that the Barbour’s Map Turtle (Graptemys barbouri) was only found in the Apalachicola River and the Escambia Map Turtle (Graptemys ernsti) was only found in the Escambia. As a matter of fact, with much of the Escambia River actually in Alabama, they were not sure whether the Escambia Map Turtle was different from the Alabama Map Turtle ( Graptemys pulchra) that inhabits the upper reaches of the Escambia River in Alabama, where they call it the Conecuh River.
Today they do now consider it a separate species and they also know these turtles are found in other rivers in the panhandle. As a matter of fact, there may be more Barbour’s Map Turtles in the Chipola River than in the Apalachicola.
Paddling the Escambia River.
Photo: Molly O’Connor
This is definitely a river turtle – preferring stronger currents with plenty of fallen trees (snags) to bask on – something they like to do a lot of. The females are twice as large as the males, with very wide heads and powerful jaws for crushing mollusk shells – their favorite food. Males are much smaller and feed primarily on insects and other aquatic invertebrates. Because of their preference for mollusk, they are usually not found in tannic rivers, like Blackwater or Perdido Rivers, where the pH is to low for successful shell development. And even on the more alluvial rivers, they are not common in the quiet backwater areas of the floodplain swamps – they really like the currents where the mollusk are.
The Barbour’s Map Turtle differs from the Escambia Map in that (a) they have circular yellow patterns on each scute (scale) of the olive green to brown carapace (top shell), (b) lack the two large yellow spots on the top of the head, behind the eye that you find in the Escambia Map, (c) lack the dark black stripe running down the middle keel of the carapace you find in the Escambia Map, (d) the rivers they inhabit.
Barbour’s Map Turtles are found in the rivers between (and including) the Choctawhatchee River and the Apalachicola River. There have been records of Barbour’s Map Turtle in the Ochlockoknee River, but it is believed they may have been moved there by humans.
The Escambia Map Turtle is only found in the Escambia, Yellow, and Shoal Rivers.
Photo: Molly O’Connor
The Escambia Map Turtle is found in rivers that feed into Pensacola Bay. These would include the Escambia, Yellow, and Shoal Rivers – again, Blackwater is too tannic. There is discussion whether the Escambia Map has been found in the Choctawhatchee, and there may be some hybridization occurring here.
On rivers where they are found, map turtles can be some of the most common turtles seen. They have high domes shells, that look more “inflated” towards the head end, and scales that form jagged points sticking up along the mid-line of the shell. This gives them a “dinosaur” appearance and another common name “sawbacks”. They are not big turtles, when compared to others like softshell, cooters, snappers – reaching a maximum shell length of 12 inches – are often seen basking on fallen trees (snags) in the water. They are skittish and hard to get close to. Many will jump into the water when you are still over 300 feet away. But for those patient enough to drift, you should get a closer look, and maybe even a picture. On one paddle I did on the Escambia River they made up over 75% of the turtles we saw in a one-mile stretch.
The Barbour’s Map prefers sections of the river where the current is strong and limestone outcrops are frequent. These limestone sections are home to a variety of snail species – the female’s favorite food. Like so many other turtles, they do have to have sandy beaches for nesting. They will venture downstream to find these where the river makes sharp turns and may venture as far as 350 feet inland looking for a suitable nesting spot. Here raccoons do their damage. They not only consume the eggs but will prey on the adults as well. It is also known that occasionally bald eagles will target map turtles as food.
Times are harder for the Barbour’s Map Turtle. In the 1950s there were reports of as many as 136 map turtles / mile. Today the numbers are more like 5-10. The decline can be attributed to several issues.
1) Human harvest. Though not as frequent today, there are records of human harvesting within their range, particularly in the Chipola River area.
2) Dams. Altering the river flow and available “snags” has impacted their numbers.
3) Removing “snags”. This is done for both navigation issues with boaters and because there are unsightly to some. However, map turtles need them – as do other riverine wildlife.
4) “Plinking”. This is a “sport” that is not as common as it once was, but still happens. This is when humans use basking turtles as target practice.
All of these, and probably others, have contributed to this decline and forced the state to protect them. They are now listed on Florida’s Imperiled Species List and you are not allowed to possess them.
The Escambia Map Turtle is still very common on the Escambia River. However, all the members of this species only live on three short rivers, and Florida is concerned that they numbers could be wiped out with a catastrophic event.
An Escambia Map Turtle in a more quiet portion of the river.
Photo: Molly O’Connor
This portion of Florida lacks the limestone substrate you find further east. The Escambia River was home to one of the greatest variety of mussels in the Florida rivers. This is their choice of food over snails. However, pollution from agriculture and a paper mill in the Alabama portion of the river, as well as altered flow and sediments due to dams in the Alabama portion, have caused a decline in the mussels. Interestingly, the non-native Asian Clam was accidentally introduced to all the river systems in the panhandle, and the map turtles love them. Some believe the introduction of the Asian Clam may have “saved” the Escambia Map.
In addition to the stressors mentioned with the Barbour’s Map, the Escambia Map has had problems with local ATVs riding all over their nesting beaches destroying nests. Because of their small geographic range, and the increase in potential threats, Florida prohibits the possession of this map turtle as well.
The cool thing about these map turtles is that they are only found in a small area of the planet – in our north Florida rivers. I hope we can protect them, and that you get to see some one day.
by Rick O'Connor | Apr 30, 2020
Okay, this is a gamble.
I began this series to celebrate the year of the Gulf of Mexico – “Embracing the Gulf 2020”. The idea was to write about the habitats, creatures, economic impacts, and issues surrounding the “pond” that we live on. I did a few introductory articles and then jumped right into the animals. We began with the fun ones – fish, sea turtles, whales – and now we are in the more unfamiliar – invertebrates like sponges and jellyfish.
But worms? Really? Who wants to read about worms?
A classic flatworm is this lung fluke.
Photo: Kansas State University.
Well, there are a lot of them, and they are everywhere. You will find in many sediment samples that worms dominate. They also play an important role in the marine community. They are great scavengers, cleaning the environment, and an important source of food in the food chains of the more familiar animals. But they are gross and creepy. When we find worms, we think the environment is gross and creepy – and sometimes it is, remember they CLEAN THE ENVIRONMENT. But worse is that many are parasites. Yes… many of them are, and that is certainly gross and creepy. Flukes, tapeworms, hookworms, leeches, who wants to learn amore about those? Well, honestly, parasitism is an interesting way to find food and the story on how they do this is pretty interesting… and gross… and creepy. Let’s get started.
According to Robert Barnes’ 1980 book Invertebrate Zoology, there are at least 11 phyla of worms – it is a big group. We are not going to go over all of them, rather I will focus on what I call the “big three”: flatworms, roundworms, and segmented worms. We will begin with the most primitive, the flatworms.
As the name implies, these worms are flat. They are so because they are the last of what we call the “acoelomate” animals. Acoelomates are animals that lack an internal body cavity and, thus, have no true body organs – there is no where for them to go. So, they absorb what they need, and excrete, through special cells in their skin. To be efficient at this, they are flat – this increases the surface area in contact with the environment. There are three classes of flatworms – one free swimming, and two that are parasitic.
This colorful worm is a marine turbellarian.
Photo: University of Alberta
The free-swimming ones are called turbellarians. Most are very small, look like leaves, very colorful, and undulate as they swim near the bottom. They have “eye-like” cells called photophores that allow them to see light – they can then choose whether to move towards the dark or not. They have nerve cells but no true brain, and one only one opening to the digestive tract – that being the mouth, so they must eat and go to the bathroom through the same opening. Weirder yet, the mouth is usually in the middle of the body, not at the head end. Some are carnivorous feeding on small invertebrates, others prefer algae, others are scavengers (CLEANING THE OCEAN). They can reproduce by regenerating their bodies but most use sexually reproduction. They are hermaphrodites – being both male and female. They can fertilize themselves but more often seek out another worm. Fertilization is internal and they lay very few eggs.
The human liver fluke. One of the trematode flatworms that are parasitic.
Photo: University of Pennsylvania
The second group are called trematodes and they are the parasites we know as “flukes”. We have heard of liver flukes in livestock and humans, but there are marine versions as well. They have adhesive organs located at the near the mouth that help hold on, and a type of skin that protects them from their hosts’ defensive enzymes. They feed on cells, mucous, and sometimes blood – yep… gross and creepy. Some are attached outside of their hosts body (ectoparasites) others are attached to internal organs (endoparasites). The ectoparasites breath using oxygen (aerobic), endoparasites are anaerobic. Like their turbellarian cousins, they are hermaphroditic and use internal fertilization to produce eggs. They differ though in that they produce 10,000 – 100,000 eggs! Their primary host (the one they spend their adult life feeding on) is always a vertebrate, fish being the most common. However, their life cycle requires the hatching larva find an intermediate host where they go through their developmental growth before returning to a primary host. These intermediate host are usually invertebrates, like snails. The eggs are released with the fish feces – a swimming larva is released – enters a snail – begins part of the developmental growth – consumed by an arthropod (like a crab) – completes development – and the crab is consumed by the fish – wah-la. The adults are usually found in the gills/lungs, liver, or blood of the vertebrate hosts. Gross and creepy.
The famous tapeworm.
Photo: University of Omaha.
Better yet are the tapeworms. We have all heard of these. They are also all parasites, but all are endoparasites. Weirder, they do not have a digestive tract. Gross and creepy. Their heads are very tiny compared to their bodies and have either four sets of suckers, or hooks, to hold onto the digestive tract of their hosts (usually vertebrates). The head is actually round but the body is very flat and divided into squares called proglottids. Each proglottid gets larger as you move towards the tail and each possesses all of the reproductive material needed to produce new worms – they too are hermaphrodites. They also have a type of skin that protects them from the enzymes of their hosts. They also require an intermediate host to complete their life cycle so the proglottids will exit the hosts body via feces and complete the cycle similar to the trematodes.
I began this with a comment on how worms benefit the overall marine environment of the Gulf. It is hard to see that in these flatworms. They are either just another consumer out there, or nasty parasites others in the community must deal with. Well… we look at the roundworms next time and see what they have to offer.
Reference
Barnes, R. 1980. Invertebrate Zoology. Saunders College Press. Philadelphia, PA. pp. 1089.
