For many of the blogs we have posted on marine life of the Gulf of Mexico I have used the term “amazing” – but these cephalopods are truly amazing. There have been numerous nature programs featuring not just marine invertebrates but rather highlighting the cephalopods specifically. We have been amazed by their looks, their colors, their intelligence, and their ferocity. They are the animals of ancient mariner legends – the “kraken”.
These are not your typical mollusk. The elongated body and lack of external shell changes everything for cephalopods.
Photo: California Sea Grant
But for us who just visit the beach to play and walk – we rarely see them. They are quite common. The squid are almost transparent in the water column as they swim and usually run deep until nighttime. The only ones I have ever encountered were hauled up in shrimp trawls – but they are usually hauled up each time, and sometimes in great numbers. Octopus are more nighttime roamers as well. I have occasionally seen them diving during daylight hours, but they are very secretive and well camouflaged. I have found cephalopods both in the Gulf and within the estuaries – again, they are more common than we think.
A study conducted in the 1950s logged 42 species within the Gulf of Mexico. Many of them live in the open sea and at depths of 350-500 feet. There are actually four types of cephalopods – the octopus and squid we know, the cuttlefish and nautilus less so because they are not common in the Gulf region.
They are mollusk but differ from their snail and clam cousins in that they have very little, if any shell. The nautilus is an ancient member of this group and still possess an external shell. However, it is chambered and can be filled with gas like a hot air balloon allowing the nautilus to hover off the seafloor – something their snail/clam cousins can only dream about.
The squid and cuttlefish have reduced their shell to a surfboard looking structure that is found internally, serving almost like backbone. It allows them some rigidity in the water column, and they can grow to greater size. Actually, the squid are the largest invertebrates on the planet, with the “giant squid” (Architeuthus) reaching lengths of 50 feet or more.
The octopus differs from the squid in that it lacks a shell all together. Thus, it is smaller and lives on the ocean floor.
Photo: University of South Florida
The octopus lack a shell all together. Without this rigid bone within, they cannot reach the great size of the giant squid – so giant octopus are legend. However, there is a large one that grows in the Pacific that has reached lengths of 30 feet and over 500 pounds – big enough!
The lack of a shell means they must defend themselves in other ways. One is speed. With no heavy shell holding you down, high speed can be achieved. Again, squid are some of the fastest invertebrates in the ocean – being clocked at 16 mph. This may not outrun some of the faster fish and marine mammals, and many fall victim to them. Birds are known to dive down and eat large numbers of them. But they can counter this by having chromatophores. These are cells within the skin filled with colored pigments that they can control using muscles. This allows them to change color and hide. And their ability to change color is unmatched in the animal kingdom. I recommend you find some video online of the color change (particularly of the cuttlefish) and you will be amazed. Yes… amazed.
The chromatophores allow the cephalopods to change colors and patterns to blend in.
Photo: California Sea Grant
To control such color, they must have a more developed brain than their snail/clam cousins – and they do. The large brain encircles their esophagus and not only be used to ascertain the colors of the environment (and how to blend in) but also has the capability of learning and memory. The octopus in particular has been able to solves some basic problems – to escape, or get food from a closed jar, for example. Many of these chromatophores possess iridocytes – cells that act has mirrors and enhance the colors – again, amazing to watch.
All cephalopods are carnivorous and hunt their prey using their well-developed vision. Squid prefer fish and pelagic shrimp. Octopus are inclined to grab crustaceans and other mollusk – though they will grab a fish when the opportunity presents itself. Cephalopods hunt with their tentacles – which are at the “head end” of the body. The squid possess eight smaller arms and two longer tentacles. Each have a series of sucker cups and hooks to grab the prey. They keep their tentacles close to their bodies and, when within range, quickly extend them grabbing the fish and bringing back to the mouth where a sharp parrot-like beak is found. They bite chunks of flesh off and some have seen them bite the head off a mackerel. I was bitten on the hand by a squid once – one of the more painful bites I have ever had.
The extended tentacles of this squid can be seen in this image.
The octopus does not have the two long tentacles – rather only the eight arms (hence its name). They move with stealth and camouflage (thanks to the chromatophores) sneaking up on their prey – or lying in wait for it to come close. Here things change a bit. Octopus possess a neurotoxin similar to the one found in puffer fish. They can bite the crab – inject the venom – which includes digestive enzymes similar to rattlesnakes and spiders – and ingest the body of the semi-digested prey after it dies. They can drill holes into mollusk shells and inject the venom within. Most will give a painful bite but there is one in the Indo-Pacific (the blue-ringed octopus) whose venom is potent enough to kill humans.
Making new octopus and squids involves the production of eggs. The male will deposit a sac of sperm called a spermatophore into the body of the female. She will then fertilize her eggs and excrete them in finger like projections that do not have hard shells. Squid usually die afterwards. Octopus will remain with the eggs – oxygenating and protecting them until they hatch. At which time they will die.
Though we have a variety of cephalopods near shore – the real grandeur is offshore. Out there are numerous species of bioluminescent cephalopods – most living at 500 feet during the day and coming within 300 feet at night. Many swim, while some float, others have developed a type of buoyant case they can carry their eggs in. Far too much to go into in a blog such as this one. I recommend you do a little searching and learn more about these amazing animals.
Enjoy the Gulf!
One of the largest groups of invertebrates in the Gulf are the Mollusk… what many call “seashells”. Shell collecting has been popular for centuries and, in times past, there were large shows where shells from around the world were traded. Almost everyone who visits the beach is attracted to, and must take home, a seashell to remind them of the peace beaches give us. Many are absolutely beautiful, and you wonder how such small simple creatures can create such beauty.
One of the more beautiful shells from the sea – the nautilus.
Well, first – not all mollusk are small. There are cephalopods that rival the size of some sharks and even whales.
Second, many are not that simple either. Some cephalopods are quite intelligent and have shown they can solve problems to reach their food.
But beautiful they are, and the colors and shapes are controlled by their DNA. Just amazing.
There are possibly as many as 150,000 different species of mollusks. These species are divided into 8-9 classes (depending which book you read) but for this series on Embracing the Gulf we will focus on only three. First up – the snails (Class Gastropoda).
There are an estimated 60,000 – 80,000 species of gastropods, second only to the insects. They are typically called snails and slugs and are different in that they produce a single coiled shell. The shell is made of calcium carbonate (limestone) and is excreted from tissue called the mantle. It covers their body and continues to grow as they do. The shell coils around a linear piece of shell called the columella. Most coil to the right, but some to the left – sort of like right and left-handed people. There is an opening in the shell where the snail can extend much of its body – this is called the aperture – and some species can close this off with a bony plate called an operculum when they are inside. Some snail shells have a thin extension near the head that protects the siphon – a tube that acts like a snorkel drawing water in and out of the body.
The black siphon can be seen in this crown conch crawling across the sand.
Photo: Franklin County Extension.
They have pretty good eyes and excellent sense of smell. They possess antenna, which can be tactile or sense chemicals in the water (smelling) to help provide information to a simple brain.
They are slow – everyone knowns this – but they really don’t care. Their thick calcium carbonate shells protect them from most predators in the sea… but not all.
Their cousins the slugs either lack the shell completely, or they have a remnant of it internally. You would think “what is the point of an internal shell?” – good question. But the slugs have another defense – they are poisonous. Venomous and poisonous are two different things. Being poisonous means you have a form of toxin within your body tissue. If a predator eats you – they will get very sick, maybe die. But you die as well, so… Not too worry, poisonous slugs are brightly colored – a universally understood signal to all predators.
There is one venomous snail – the cone snail, of which we have about five species in the Gulf. They possess a stylet at the tip of their siphon (similar to the worms we have been writing about) which they can use as a dart for prey such as fish. Many gastropods are carnivores, but some are herbivores, and some are scavengers.
Many shells are found on the beach as fragments. Here you see the fragment of a Florida Fighting Conch.
Photo: Rick O’Connor
Most have separate sexes and exchange gametes in a sack called a spermatophore. Fertilized eggs are often encased in structures that resemble clusters, or chains, of plastic. These are deposited on the seafloor and the young are born with their shell ready for life.
This group is not as popular as a food item as other mollusk but there are some. The Queen Conch is probably of the most famous of the edible snails, and escargot are typically land snails. I am not aware of any edible slugs… and that is good thing.
Some of the more common snails you will find along our portion of the Gulf of Mexico are:
Crown Conch Olive Murex Banded Tulip
Whelks Cowries Bonnets Cerith
Slippers Moon Oyster Drills Bubble
The most encountered slug is the sea hare.
A common sea slug found along panhandle beaches – the sea hare.
I hope you get a chance to do some shelling – I hope you find some complete ones. It is addictive!
Well, maybe not…
But there could be reason to keep an eye out. We are not talking about the common ribbed or hooked mussels we found in the Pensacola Bay area. We are talking about an invasive species called the green mussel (Perna viridis).
The green mussel differs from the local species by having a smooth shell and the green margin.
Photo: Maia McGuire Florida Sea Grant
Why be concerned?
By nature, invasive species can be environmentally and/or economically problematic. In this case, it is more economic – which is unusual, most are more environmental concerns. The big problem is as a fouling organism. Like zebra mussels (Dreissena polymorpha), green mussels grow in dense clusters, covering intact screens to power plants, intact pipes to water plants, and can displace native spaces by competing for space. It has been determined they can grow to densities of 9600 mussels / m2 (that’s about 10 ft2) and they can do this on local oyster reefs – displacing native, and economically important, oysters. They grow quickly, being sexually mature in just a few months, and disperse their larva via the currents. To make things more interesting, they may be host to diseases that could impact oyster health.
So, what is the situation?
They are from the Indo-Pacific region, found all across southeast Asia and into the Persian Gulf. In this part of the world they are an aquaculture product. There was interest in starting green mussel aquaculture in China, and in Trinidad-Tobago. After they arrived in Trinidad, they were discovered in Venezuela, Jamaica, and Cuba – it is not believed this was due to re-locating aquaculture, but rather by larva dispersal across the sea… they got away.
This cluster of green mussels occupies space that could be occupied by bivavles like osyters.
It would be an easy jump from Cuba to Florida – and they came. The first record was in 1999 in Tampa Bay. They were found while divers were cleaning an underwater intake screen. Dispersal could have happened via larva transport in the currents, but it could have also occurred via ship ballast discharge at the port – this is how folks think it got there, they really do not know. From there they began to spread across the peninsula part of the state. They have been reported in 19 counties, most on the Gulf coast, and there is a record from Escambia County – however, that one was not confirmed.
How would I know one if I saw it?
They prefer shallow water and are often found in the intertidal zones – attached to pilings, seawalls, rocks. As mentioned, they grow in dense clusters and should be easy to find. They are long and smooth, with a mean length of 3.5 inches. There was one found in Florida measuring 6.8 inches, which they believe is a world record. Mussels differ from oysters in that they attach using “hairy” fibrous byssal threads – in lieu of cementing themselves as oysters do. As mentioned, the shell is smooth and may have growth rings, but it lacks the “ribbed” pattern we see on the local ribbed and hooked mussel. It will have a green coloration along the margin – hence its name, and the interior of the shell will be pearly white.
The shell at the far right is the common ribbed mussel native to our local salt marshes. Just to the left is the invasive green mussel. Can you tell them apart?
Photo: Maia McGuire Florida Sea Grant
They prefer salinities between 20-28‰, which would be the lower portions of the Pensacola Bay system (Santa Rosa Sound, Big Lagoon, maybe portions of Pensacola Bay). They are not a fan of cold water. They do not like to be in water at (or colder) than 60°F. Some biologist believe it is too cold in the panhandle for these bivalves, but we should report any we think may be them – to be sure.
What do we do if found?
1) Get a location and photos. Pull some off and get up close photos of an individual.
2) Report it. You can do this by contact the Escambia County extension office (850-475-5230 ext.111), or email me at email@example.com.
3) If there is a method of removing all of them, do so. But this should be done only after the identification is verified. When removing try to collect all the shell material. The fertilized gametes within, if left, can still disperse the animal.
4) They are suggesting boat owners check their vessels when trailering. Avoid transporting them from one body of water to another.
5) I would recommend that marina owners do the same – check boats and pilings.
It appears the mean temperature of the Gulf is increasing. With this change it is possible some of the tropical species common in south Florida could disperse to our region, and that could include the green mussel. The most effective (and cheapest) way to manage an invasive species is catch them early and remove them before they can become established.
For more information on green mussels in Florida read https://edis.ifas.ufl.edu/pdffiles/SG/SG09400.pdf.
Baby terns on Pensacola Beach are camouflaged in plain sight on the sand. This coloration protects them from predators but can also make them vulnerable to people walking through nesting areas. Photo credit: UF IFAS Extension
The controversial incident recently in New York between a birdwatcher and a dog owner got me thinking about outdoor ethics. Most of us are familiar with the “leave no trace” principles of “taking only photographs and leaving only footprints.” This concept is vital to keeping our natural places beautiful, clean, and safe. However, there are several other matters of ethics and courtesy one should consider when spending time outdoors.
- On our Gulf beaches in the summer, sea turtles and shorebirds are nesting. The presence of this type of wildlife is an integral part of why people want to visit our shores—to see animals they can’t see at home, and to know there’s a place in the world where this natural beauty exists. Bird and turtle eggs are fragile, and the newly hatched young are extremely vulnerable. Signage is up all over, so please observe speed limits, avoid marked nesting areas, and don’t feed or chase birds. Flying away from a perceived predator expends unnecessary energy that birds need to care for young, find food, and avoid other threats.
When on a multi-use trail, it is important to use common courtesy to prevent accidents. Photo credit: Carrie Stevenson, UF IFAS Extension
- On a trail, the rules of thumb are these: hikers yield to equestrians, cyclists yield to all other users, and anyone on a trail should announce themselves when passing another person from behind.
- Obey leash laws, and keep your leash short when approaching someone else to prevent unwanted encounters between pets, wildlife, or other people. Keep in mind that some dogs frighten easily and respond aggressively regardless of how well-trained your dog is. In addition, young children or adults with physical limitations can be knocked down by an overly friendly pet.
- Keep plenty of space between your group and others when visiting parks and beaches. This not only abides by current health recommendations, but also allows for privacy, quiet, and avoidance of physically disturbing others with a stray ball or Frisbee.
Summer is beautiful in northwest Florida, and we welcome visitors from all over the world. Common courtesy will help make everyone’s experience enjoyable.
Sea pork comes in a wide variety of shapes and sizes. Photo credit: Carrie Stevenson, UF IFAS Extension
Recently I was walking the beach, enjoying a sunset and looking around at the shells and other oddities in the wrack line where waves deposit their floating treasures. Something bright green and oblong caught my eye. It was emerald in color, smooth yet fuzzy at the same time, and firm to the touch. At first, I thought it was a sea bean–a collective term for the many species of seeds and fruits that float to our shores from tropical locations in the Caribbean or Central/South America. The bright green definitely seemed like something botanical in nature. However, the vast majority of sea beans have a woody, protective shell similar to our more familiar pecans or acorns.
I remembered a family member asking about finding a mystery chunk of pink mass she found on the beach a few years ago. It resembled a pork chop more than anything else.
A different variety of sea pork that really lives up to its name. Photo credit: Stephanie Stevenson, Duval County Master Gardener
Looking closer and consulting a couple of resources, I realized we had both (most likely!) happened upon one of the oddest and often-questioned finds on our beaches: sea pork. Ranging in color from beige and pale pink to red or green, sea pork is a tunicate (or sea squirt), a member of the Phylum Chordata, home to all the vertebrate and semi-vertebrate animals. While they look and feel more like a cross between invertebrate slugs or sponges, the tunicates are more advanced organisms, possessing a primitive backbone in their larval “tadpole” form. Despite their blob-like appearance, they are more closely related to vertebrate animals than they are to corals or sponges.
The unusual life cycle of the tunicate. Photo credit: University of Washington, used with permission with Florida Master Naturalist program
During their short (just hours-long) larval stage, the tunicate larvae uses its nerve cord (supported by a notochord similar to a vertebrate spine) to communicate with a cerebral vesicle, which works like a brain. Similar to fish, this primitive brain uses an otolith to orient itself in the water, and an eyespot to detect light. These brain-like tools are utilized to locate an appropriate location to settle permanently. Using a sticky substance, the tunicate will attach its head directly to a hard surface (rocks, boats, docks, etc.) and go through a metamorphosis of sorts. The tunicate reabsorbs its tail and starts forming the shape and structure it needs for adulthood.
As an adult, the organism has a barrel shape covered by a tough tunic-like skin (hence “tunicate”). Adult bodies have two siphons, one to bring water in, another to shoot it out (giving them their other nickname, the sea squirt). The water passes through an atrium with organs that allow it to filter feed, trapping plankton and oxygen. The tunicates will spend most of their lives attached to a surface, pumping water in and out as filter feeders. They may be solitary or live in colonies, and vary widely in color and shape, lending variety to those chunks of sea pork found washing up.
I am still awaiting positive identification from an expert on my green find to confirm that it is, indeed, a tunicate and not an unfamiliar plant. Consulting with Extension colleagues, for now we are pretty confidently going with green sea pork. If you have seen one of these before or something resembling sea pork, let us know! It is fascinating to see the variety and unusual shapes and colors.
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.