Killifish of the Florida Panhandle

Killifish of the Florida Panhandle

Like many of you reading this article, I grew up here in the northern Gulf coast.  I spent a lot of time at the beach and in the water enjoying this fantastic place people use to call the “miracle strip” and now call the “emerald coast”.  I would spend hours swimming, fishing, crabbing, skiing (a sport that has all but disappeared around here), and just enjoying this place.  With all the fishing and snorkeling we did we were familiar with many species in the area.  Pinfish, flounder, mackerel, croaker to name a few.  But one group of local fish I was not aware of were the killifish.  I was not aware of them until I attended Dauphin Island Sea Lab to study marine biology.  And then… I discovered them.

 

Like many who entered marine biology programs in the 1970s I was going to be an ocean going “Jacques Cousteau” studying sharks or something.  But at Dauphin Island I was introduced to the amazing world of the estuary where we did a lot of work in Mobile Bay.  Pulling seine nets through the numerous salt marshes over there I quickly found that one of the most abundant fish there were these fish known as killifish.  They are small minnow type fish who typically run three inches or so in length.  There are two who grow larger, the longnose killifish and the gulf killifish both can reach six inches and are known by local fishermen as “bull minnows”.  Bull minnows are popular bait, but most fishermen do not know that the actual name of these fish are killifish.  When I was in graduate school, I took a course in aquaculture, and we visited five states in five days stopping at federal, state, and private fish farms.  One private farm was a “bull minnow” farm in Arkansas.  This farmer was doing quite well.  He had a collection of corvettes and was working on a collection of mustangs.  Needless to say bull minnows are a popular bait.

 

But who are these abundant estuarine minnows that most are not aware of?

 

Well, as we said they are small.  For most, their bodies are tube shaped (fusiform) and their fins are rounded, not forked.  Rounded fins (truncate) are not designed for speed but for better maneuvering in and around grasses, rocks, and coral.  Killifish live in the grasses of seagrass beds and shoreline marshes where these fins come in handy.

 

Most have an extreme tolerance for changes in salinity.  The sheepshead minnow (Cyprinodon variegatus) can live in salinities as low as 0 ppt and as high as 100 ppt – mean seawater salinity is 35 ppt.  Because of this high tolerance to salinity changes, many of these killifish can be found in a variety of habitats within the estuary and even in freshwater systems entering the bay.  One species, the longnose killifish (Fundulus similis) seems to prefer more saline conditions.  Because of this we are looking at a local project to determine which estuarine creeks this species is found.  The absence of the longnose killifish could suggest freshwater discharge and, possibly, a run-off issue.  But with the dramatic salinity shifts typically seen within estuaries due to tides and run-off, having a high tolerance for salinity shifts is a good adaptation to have.

 

According to Hoese and Moore1 there are seven species of killifish within the estuaries of the northern Gulf of Mexico.

This longnose killifish has the rounded fins of a bottom dwelling fish.

The longnose killifish (Funuduls similis) is elongated with vertical black stripes and a single dot at the base of the tail.  It has an elongated snout that gives the name “longnose”.  This is a very common killifish but, as mentioned above, disappears when salinities become too low.  According to Hoese and Moore1 this fish is not that common along the Gulf coast of peninsula Florida.  The biogeographical reason?  Not sure.  We know this fish does not like freshwater but the discharge in that part of the Gulf is not that different than the panhandle, in fact, it could more saline.

Saltmarsh topminnow
Photo: Florida Fish and Wildlife Conservation Commission

The saltmarsh topminnow (Fundulus jenkinsi) is not as common.  Its geographic range extends from Galveston Bay to the western Florida panhandle.  Here in Florida, it is so rare it is a listed species.  It resembles the longnose in shape and vertical stripes, which are actually rows of black dots, but the snout is short.  I am not sure why this fish has not expanded its range east into the Big Bend or west towards Corpus Christi.  Both of those areas seem to be higher in salinity and this may be the reason.

 

The gulf killifish (Fundulus grandis) is the “big boy” of the group.  With a mean length of six inches this fish is often confused with “fingerling mullet” and is very popular as bait.  This is the fish most often called “bull minnow”.  Young will have dark stripes like the longnose but lack the “longnose” and does not have a black spot at the base of the tail.  Most lose their stripes when they become older.  It is found throughout the Gulf region.

 

The bayou killifish (Funudulus pulvereus) is another very common killifish in our area.  Smaller than the gulf killifish and longnose, it can be identified by the yellowish colored anal fin.  Males will have stripes while females will have spots.  The coloration of these is amazing and the breeding colors of the males even more so.  Hoese and Moore1 report this fish only from southern Texas to Alabama, but we have often found them here in Pensacola.  I am not sure how far east they exist, but there must be some barrier in Florida waters to impede their dispersal there.

Sheepshead Minnow
Photo: University of Florida

The sheepshead minnow (Cyprinodon variegatus) is the champion of salinity tolerance.  They are found in many estuarine habitats and even some extreme ones where no other fish are found.  Hoese and Moore1 report that it has the highest tolerance of any fish in the world.  There are records of this fish living in waters over 100 ppt (note: the average salinity for the ocean is 35 ppt).  As you might expect, it has the largest range as well.  This fish had been reported from Maine, down the entire east coast, the Gulf of Mexico, and as far south as Venezuela.  It is not as elongated as most killifish, having a more short and stout appearance.  They have dark vertical bars on their bodies and the males produce a beautiful iridescent blue color on their backs during breeding.

 

Diamond Killifish
Photo: University of Florida

The diamond killifish (Adinia xenica) is one that I have not collected very often.  It resembles the sheepshead minnow is shape and color but has a more pointed snout and the teeth are compressed instead of conical, as they are in the sheepshead minnow.  This fish is restricted to the western Gulf of Mexico but is found here in the Florida panhandle.  It usually is in a group with other killifish, so, you would have to look hard in your sample to see if you have it.

 

Rainwater Killifish
Photo: Florida Museum of Natural History

Finally, there is the rainwater killifish (Lucania parva).  This is a more elongated form with no markings on the body at all.  At first glance, after seeing other types of killifish, it would not appear to be a killifish at all.  It is one of the smaller killifish (2 inches) and is often found in freshwater creeks feeding into the bays.  The males will have a reddish-orange anal fin during breeding season.  It does have a large range extending from New England to Mexico.

 

These are truly amazing fish.  They are extremely abundant and hardy.  For those prone to use small nets collecting fish along the shorelines, grassbeds, and salt marshes, they will find this group very common, and most do well in aquariums.

 

Reference

 

1 Hoese, H.D., Moore, R.H. 1977. Fishes of the Gulf of Mexico; Texas, Louisiana, and Adjacent Waters. Texas A&M Press, College Station TX. Pp. 327.

Wildlife on the Beach in January

Wildlife on the Beach in January

During 2022 I plan to make weekly hikes on Pensacola Beach to see what sort of wildlife, or other natural phenomena, I encounter each month.  For the first January trip I did a short hike at Ft. Pickens on the west end of Santa Rosa Island.

 

Ft. Pickens is more wooded than much of the island and provides both maritime forest and beach habitats for a variety of wildlife.  On my first trip – Jan 6 – the temperature was 62°F and overcast.  It actually rained some during the hike.  As I approached the fort area, I saw a bald eagle sitting on a sand dune.

A bald eagle sitting on a dune near Pensacola Beach.
Photo: Rick O’Connor

Everyone gets excited about seeing a bald eagle.  Its like dolphins, no matter how many times you see them, it is still cool, and you alert everyone they are there.  The difference with bald eagles is that they were not always here.  Growing up in Pensacola I rarely saw one.  I worked for a period of time on what were called “the ponds” on the property of Air Products in Pace, Florida.  The ponds were a water treatment system to help improve water quality coming from the plant being discharged into Escambia Bay.  It was a wildlife sanctuary and there was plenty of wildlife there.  Cottonmouths, deer, turtles, raccoons, and alligators were all common.  One of the largest eastern diamondback rattlesnakes I have ever seen was found there.  And, during the winter months, we would occasionally get a bald eagle.  It was rare and very exciting.

 

A field guide of Birds of the Eastern United States published by Roger Tory Peterson in 1980 indicates that their winter breeding range includes much of Florida.  A document published by the U.S. Fish and Wildlife suggest they begin building nests in our area in September, lay eggs by October, and hatching occurs in November.  Between November and March, the parents take care of them until the fledge and head out on their own.  The reason we have not seen more in our younger years was their population was down.  The decline of the national bird was due to a variety of reasons, but the DDT story played a role.

 

Today their numbers have rebounded and encounters with them in our area have increased.  Their nest can be quite large and are usually close to a water source.  These birds are known as predators but actually spend a lot of time feeding on carrion and robbing other birds of their food source.  Competition between the osprey, another recovering species, and bald eagles are quite famous.  And, like I said, you never get tired of seeing them.  This time of year, you can spot them in several locations around the beach areas.

 

Other creatures found on this January hike at Ft. Pickens included:

Great blue herons use tall pines for nesting during winter.
Photo: Rick O’Connor

Mockingbirds are quite common in the winter. This one was feeding on the red berries of a yaupon holly.
Photo: Rick O’Connor

 

 

 

 

 

 

 

 

 

This green blob is actually a sea slug known as a sea hare. It was returned to the water.
Photo: Rick O’Connor

This structure is often found on panhandle beaches. It is the egg case of the snail known as the moon snail. Also called the “shark’s eye” or “cat’s eye”.
Photo: Rick O’Connor

 

 

 

 

 

 

 

 

 

 

Unfortunately dead seabirds on the beach are not uncommon. This one is a pelican.
Photo: Rick O’Connor

 

 

 

 

 

 

 

 

 

 

I encourage to take some time this winter and go for a hike and see what you can discover.

Needlefish of the Florida Panhandle

Needlefish of the Florida Panhandle

I remember first seeing a needlefish as a young boy on Pensacola Beach.  We were either playing or snorkeling in Santa Rosa Sound and one of these long, sleek, “barracuda” looking fish swam by cruising the surface of the water.  Your first reaction is danger.  They have long jaws with very sharp teeth and move very “predator-like” through the water.  Your fear is that if you get too close, they will turn and attack.  I remember following them for several minutes watching how they looked at me but continued to search for prey.  I was never attacked.

The Atlantic needlefish.
Photo: U.S. Geological Survey

Years later, as a marine science teacher, we were conducting a diversity and abundance study of nearshore fishes of the Pensacola Bay area.  We would often catch these in our seine nets, and they would often get their numerous teeth snagged in the net.  It took a careful maneuvering to remove them but in doing so, we could see their “nasty” side.  They would try to bite, and bitten I was a few times.  The needle like teeth did hurt a little and always drew blood.  But once released they never turned on us, nor did the needlefish that were in the net and not snagged.  We simply just released them.

 

I have often been asked by students “what do they eat?”.  I have never read about, nor conducted a study, on their diet but would guess they prey on small fishes.  Needlefish themselves are not terribly large, two feet being reported as the average length, so their prey could not be very large.  Their long skinny snout and relatively small mouth with the lack of molars would suggest they must grab and swallow, almost whole, whatever lunch would be for that day.  Fish that are only a few inches long at most.  I have heard silversides, and killifish are popular targets for them, I can see this.  I have seen them hunt in small groups, but mainly I see them alone.  They themselves would be prey for larger predatory fishes in the bay area and birds, such as osprey, would hunt them due to their habitat of hunting at, or near, the surface.

Swimming near the surface is a common place to find needlefish.
Photo: Florida Springs Institute

Though Hoese and Moore1 report four species in our area, it is the Atlantic Needlefish (Strongylura marina) that I caught most often.  Honestly, it is very hard to tell the species apart just by looking at them.  One, the Keeltail Needlefish (Platybelone argalus) lacks gill rakers, if you know what those are, and this cannot be determined unless you catch the fish and take a peek.  That said, I did capture these while conducting that fish diversity study with my marine science class.  Like the Atlantic Needlefish, the Flat Needlefish (Ablennes hians) and the Houndfish (Tylosurus crocodilus) – you have to love that name “crocodilus” – have gill rakers and are differentiated by the number of rays on their anal fins.  Another feature not easily noticed while snorkeling with them.  I have heard the Houndfish can be aggressive.  Hoese and Moore report they are more common offshore.  We did capture one in Pensacola Bay and did not notice a “nastier” attitude.

 

All four species have a wide geographic range; found along the Atlantic coast, throughout the Gulf of Mexico and the Caribbean, south to Brazil.

 

They are a common and interesting fish to see, and not dangerous as they may appear.

 

Reference

 

1 Hoese, H.D., Moore, R.H. 1977. Fishes of the Gulf of Mexico; Texas, Louisiana, and Adjacent Waters. Texas A&M Press.  College Station, TX. Pp. 327.

Batfish of the Florida Panhandle

Batfish of the Florida Panhandle

This is another one of those fish in this series that is not often seen but when you do see one you will ask “what is that?” – So, we will answer the question by including it here.

 

Like the frogfish we have already written about, batfish are described by Hoese and Moore1 as “grotesque” and they take it a step further by telling us all “ugly” fish (as they say) are grouped into what many call “dogfish”.  As with the frogfish, I am not sure I would use the term grotesque, but they are strange looking.

Juvenile Polka-Dot Batfish (Ogcocephalus radiatus) in the polluted intracoastal waterway in Palm Beach County, FL.
Photo: Science Photo Library

I have only seen a couple in my life.   Hoese and Moore mention they are often brought up in shrimp trawls, and I have seen them while doing trawl surveys at Dauphin Island Sea Lab.  I also found one while snorkeling along a seawall near Gulf Breeze FL.  So, they are out there just not encountered as often, or as well known, or seen as frequently, as many other fish in the Gulf.  Another reason to include this group here.

 

It is hard to describe what this fish looks like.  They are, as they say, dorso-ventrally flattened – meaning from top to bottom, not side to side – like a stingray.  They have two fins extending from parts of their body that sort of “stick out of the side” and appear to be like webbed feet with which they walk.  Actually, there are these small, modified fins on the ventral side that are used to walk on the bottom – they are bottom dwelling (benthic) fish for sure.  Like their relatives the frogfish they have a modified spine that is used like a fishing lure.  Like the frogfish, the shape of that lure can be used to identify species.  But unlike the frogfish the lure is located between their mouth (which near the bottom of the body and is very small) and a pointed rostrum that extends from the top of their head like a battering ram.  This lure is extended to lure not fish swimming above, as with the frogfish, but small creatures in and on the sand.  Because of this they do not call the lure an illicium but a esca.  These are strange looking fish.

 

Hoese and Moore list four different species and indicate there are at least three others in the Gulf of Mexico.  Most are associated with the continental shelf of the Gulf and not inland where we might see them snorkeling around.  A couple of species are more associated the continental slope, which drops from the continental shelf to the deep sea.  But the Polka-dot batfish (Ogocephalus cubifrons) is reported as being inshore and is the species I have encountered.

 

Many species are only described as being from the shelf of the Gulf of Mexico and no other oceans.  Some of them are even more restricted to either the eastern or western Gulf.  This all suggests that batfish do have biogeographic barriers of some sort restricting their dispersal.  Being offshore benthic fish, your first guess would be substrate.  Usually in those locations the temperature and salinities are pretty similar but the material on the bottom (rock, shell, sand, canyons, etc.) are not.  However, several articles mention that batfish can be found over rocky or sandy bottom2,3,4 and the polka-dot batfish can be found in grassbeds as well2.  So, I am not sure what the possible barrier is, but several do have a limited range.  The east-west split could very well be the DeSoto Canyon off the coast of Pensacola.

 

All of that said, it is a very interesting group of fish that for one species you might encounter while out and about snorkeling or diving in the Florida panhandle.

 

References

 

1 Hoese, H.D., Moore, R.H. 1977. Fishes of the Gulf of Mexico; Texas, Louisiana, and Adjacent Waters.  Texas A&M Press.  College Station, TX.  Pp. 327.

 

2 Ogocephalus cubifrons, Polka-dot batfish. 2017. Discover Fishes. Florida Museum of Natural History.  https://www.floridamuseum.ufl.edu/discover-fish/species-profiles/ogcocephalus-cubifrons/.

 

3 The Red-lipped Batfish. 2014.  Ashland Vertebrate Biology. Ashland University, Ohio.  http://ashlandvertbio.blogspot.com/2014/12/the-red-lipped-batfish.html.

 

4 Cocos Batfish, Ogocephalus porrectus. 2015. Smithsonian Tropical Research Institute.  https://biogeodb.stri.si.edu/sftep/en/thefishes/species/777.

A Sea of Christmas Lights

A Sea of Christmas Lights

Most people would agree that this is one of the best times of the year.  Christmas brings great music, great cooking, great family gatherings, and… great lights.  The lighting of Christmas is one of the more beautiful parts of these celebrations and as I thought about Christmas and writing about nature I thought of those lights.

There is nothing like Christmas lights on a tree.
Photo: Molly O’Connor

Nature can produce beautiful lights as well.  Mostly found in the ocean – “phosphorus”, as many called it when I was growing up here, is a beautiful spectacle.  It is hard to see with our artificial lights but in the warmer months of summer at locations far from the artificial lights of people, the sea glows a blue-green color that is amazing.  Many see this light as sparkles in the water as the waves roll by.  Others see it as a stream of light as a fish, or something else, moves around.  In the right conditions, you can see your footprints glow as you step in the wet sand.  I remember diving at night under the Bob Sikes Bridge once in the 1970s when the bridge, and all of the divers, were aglow.  It was beautiful.  This phenomena have amazed scientists for centuries and trying to understand how it is produced was a quest for many.

 

The term phosphorescence actually means using light to emit light.  Turns out that is not what is happening in this case.  Scientists found that some creatures posses a group of molecules known as luciferins.  The term lucifer means “producing light” or “morning star” and seemed an appropriate name for this group of molecules.  When luciferin is oxidized, the transfer of an electron emits a “cool light” – usually blue-green in color.  Cool meaning that less than 20% of the emitted light is lost as heat.  There is a catalytic enzyme known as luciferase that can increase the speed of this chemical reaction and produce bright light in seconds.  Since this light is produced by a chemical reaction it was called “chemiluminescence”.  However, since this reaction is produced and controlled by living organisms is more widely known as “bioluminescence”.  It is not phosphorescence.

Bioluminescence in the sea.
Photo: North Carolina Sea Grant

 

There are many creatures that produce bioluminescence.  The famous fireflies are one, but most live in the sea.  The “phosphorus” we are used to seeing is produced by small single celled plants in a group known as dinoflagellates.  When disturbed they emit blue-green light as a flash and then a slow dim.  Fish swimming past, waves crashing on the beach, or boat and propeller pushing through the water will disturb them.  The warmer the sea, the more dinoflagellates there are, the more amazing the light show is.  There are lagoons in the tropical parts of the world where these small plants are trapped due to a small opening in and out of the lagoon.  The entire lagoon can light up when the conditions are right.

Noctiluca are one of the dinoflagellates that produce bioluminescence.
Photo: University of New Hampshire.

 

But it does not stop with dinoflagellates.  As you descend into the deep ocean the bioluminescence becomes even more spectacular.  All sorts of creatures from jellyfish to squid, to fish, to even fungus and bacteria illuminate.  Some species of luminescent marine animals do not produce the light themselves but rather harbor luminescent bacteria on the skin or specially designed skim pockets to hold them.  Though blue-green is the dominant color, yellows, oranges, and reds have been produced.  It has been suggested that blue-green is much easier to see in the deep so reds and oranges are less likely.  That said, it is believed that some marine creatures will produce those colors to assist in capturing prey.  They can see the red light, but their prey cannot.

The magical lights of the deep sea.
Photo: NOAA

 

Either way the illumination of the ocean, like the Christmas illumination of our streets and homes, is beautiful and amazing thing.  As you admire the lights on the neighborhood home, find some short videos of bioluminescence online and enjoy the show.  Happy Holidays everyone.

Frogfish of the Florida Panhandle

Frogfish of the Florida Panhandle

Hoese and Moore1 describes members of the frogfish family as “grotesque”.  Well… maybe.  I am not sure I would call them grotesque, but they are sort of gelatinous blobs with reduced or missing scales.  They feel sort of “mushy”.  They have broad shaped fins and a free dorsal spine that serves as a “fishing rod and lure” called the illicium.  Maybe they are a little grotesque…maybe.

 

Being round with broad fins, this is a very slow swimming fish, if you can call how they move swimming.  So, to survive, they must blend in with the environment to avoid predators and wait for their prey to come within range before pouncing on them.  The illicium lures prey to within range and their “gulp” is like a vacuum cleaner sucking food out of the water.

 

The family name for the group is Antennariidae, which is appropriate being they have that fishing lure, and is one of the few fish families whose gill opens are behind the pectoral fin.  There are 48 species of frogfish found worldwide and most are tropical and subtropical2.   Hoese and Moore1 indicate there are three species found in the Gulf of Mexico and all three can be found along the Florida panhandle.

 

The most commonly encountered frogfish in our area is the Sargassum fish (Histro histro).  This small six-inch fish blends in perfectly with the sargassum mats that float in close to shore.  Using its fins to brace itself in the seaweed, this fish uses its illicium to attract a variety of small prey that live in the sargassum community.  As the sargassum mats are blown close to shore the sargassum fish will leave and move to another mat further out.  Finding them on the beach is rare but snorkeling out to a mat just offshore with a small hand net, you might be able to find one by scooping up some sargassum and taking a look.

This sargassum fish is well camelflouged within this mat of sargassum weed.
Photo: Florda Museum of Natural History

 

The Singlespot Frogfish (Antennarius radiosus) is even smaller at three inches and is found on hard habitats of the middle continental shelf offshore, but occasionally is found along the coastline.

 

The Splitlure Frogfish (Phrynelox scaber) is five inches in length and not as common on our shelf as the singlespot frogfish.  Those that have been found off our coast were further offshore.

 

The Florida Museum of Natural History includes the Striated Frogfish (Antennarius striatus) as a Gulf species and resident of panhandle waters3.

 

The distribution of this group is pretty wide throughout the tropical and subtropical waters of the Atlantic Ocean and beyond – suggesting few geographic barriers to dispersal.  The sargassum fish, of course, is restricted where sargassum is found – but sargassum is found in a lot of places.  The singlespot frogfish seems to have a more restricted home range found in Bermuda, the Atlantic coast of Georgia and Florida, and the Gulf of Mexico.  Hoese and Moore does not report this fish in other parts of the Caribbean as the others are1.

 

They may be grotesque to some, but to others it is an amazing group of fish, much fun in an aquarium, and exciting to find when snorkeling or diving.

 

1 Hoese H.D., Moore R.H. 1977. Fishes of the Gulf of Mexico; Texas, Louisiana, and Adjacent Waters.  Texas A&M University. College Station TX. Pp. 327.

 

2 Family Antennariidae – Frogfish. 2012. FishBase. https://www.fishbase.de/summary/FamilySummary.php?ID=192.

 

3 Antennarius striatus. 2017. Discover Fishes. Florida Museum of Natural History.  https://www.floridamuseum.ufl.edu/discover-fish/species-profiles/antennarius-striatus/.