Recently I was walking along the shore of Santa Rosa Sound near Park West searching for horseshoe crab nesting. I did not find any nesting activity, but the beach was covered with small comb jellies. These creatures reminded me of my childhood days on Pensacola Beach when we used to throw them at each other – “football jellyfish” we would call them. Now that I am an adult, I understand throwing comb jellies was not a good thing, but as a kid it was the thing to do. I mean, these are jellyfish that do not sting. How cool is that. It occurred to me that many reading this article also experienced comb jellies as a kid the way I did, but probably know very little about the animal that was bringing them enjoyment. So, let’s learn a little more about this magical creature.
Comb jellies do not sting and they produce a beautiful light show at night.
The typical jellyfish we encounter at the beach is in the Phylum Cnidaria. They have gelatinous bodies made of a material called mesoglea. They have only one opening into their gut – the mouth, which serves both taking food in and releasing waste. They have a thin tissue called the velum which they undulate allowing them to slowly pulsate through the water column. Extending from their “bell” are tentacles armed with cells called cnidoblast (where they get their phylum name) which house a coiled harpoon possessing a drop of venom called a nematocyst. They use these nematocysts to paralyze their prey, which – depending on the jellyfish and the type of venom they have – range from small planktonic creatures to decent sized fish. To find their prey is a trick. They do have nerves but lack a central nervous system (brain) and so they are aware of what is going on around them, and can react, but memory and thought is not high on their ability list. The tentacles extend into the water column hoping to accidentally snag something to eat. Another thing about cnidarians, is that some do not look like jellyfish at all. Some, like the sea anemones and corals, look more like flowers attached to rocks extending their tentacles up into the water column hoping to get lucky.
The nonvenmous comb jelly.
Photo: Bryan Fluech
Our friend the comb jelly is in the Phylum Ctenophora. They too have a gelatinous mesoglea body with only a mouth. However, their method of swimming is different. Instead of an undulating velum, they have grooves along their sides that house a row of cilia (hair-like structures) that move in a pattern similar to you running your finger over the bristles of a hair comb. These are called ctenes and is where the animal gets its common name “comb jelly”. Some species have tenacles, but our local one does not. Either way there are no cnidoblast or nematocysts. Rather they move through the water column, usually with their mouths facing upwards, collecting planktonic food and, in some cases, other comb jellies. They also lack a brain but have the nerve net and they also possess a structure called a statocyst that lets them know whether they are upside down or not. In this group there are only medusa (the swimming form), the polyps (flower-like form) found in cnidarians is not found in this group. However, they do something that our local jellyfish do not do. They emit light. The cells that do this are located in the grooves where the ctenes are located. The light they produce is blue in color and is magical when hundreds are doing this at night. They use oxygen to produce this light. It first appears bright, but as the oxygen is used it becomes dimmer.
We saw them as something to play with when we were kids. We see them now as a neat member of our marine community and a magical part of living at the beach. Comb jellies are just cool.
For many who grew up in the Pensacola area October meant flounder gigging season. This once popular past time involved going out at night along the shores of Santa Rosa Sound with flounder lights and gigs seeking a local favorite flounder. Everyone has their favorite recipe for this fish but in this article, we are going to focus on the fish – maybe something you did not know about it.
In the northern Gulf of Mexico, flounder are flatfish with the two eyes on the left side of the head. Locally, flatfish with eyes on the right side are called soles. We do have native soles, but all species are too small to be a food option. If you are not familiar with the “two eyes on one side of the head” idea, yes – flounder hatch from the egg looking like a normal fish, an eye on each side of the head. But earlier in development one eye slides across to the other side. This is a weird transformation and there are probably videos online, so you see how this happens – check them out. The reason for this transformation is to improve depth perception. Eyes close together give the animal binocular vision. Binocular vision does not have a wide viewing range, can basically see what is in front of it but not so much what is behind it, but it does give the animal good depth perception, it can tell how far away the prey actually is, and this is important when hunting.
Once the eyes have shifted to the left side of the head, flounders lose the pigments on the side without eyes, which becomes white, and the fish lays on its side – white side down. The cells on the “eye side” have chromatophores that allow the fish to change color to match the sand on the bottom. Another important feature of being a successful hunter. Most of know they will bury themselves in this sand as well. With their binocular vision, camouflaged body, and sharp teeth, they lie in wait to ambush predators.
You may also be surprised at how many different kinds of flounder are found in the northern Gulf of Mexico. There are 21 species listed, and they range in size from the small Spiny Flounder which can reach an average length of 3 inches, to the Southern Flounder which attains a length of 3 feet. The Gulf flounder and Southern flounder are two species that are popular seafood targets, but any decent sized flounder will do.
Flounder are found in a variety of habitats ranging from shallow seagrass beds nearshore, near structure just offshore, to artificial reefs and the base of bridges, to depths of 1200 feet in the Gulf of Mexico. Many species spend the warmer months in the estuaries moving offshore when the weather cools down to spawn. Hard northerners can trigger a mass migration and a great time for commercial and recreational fishermen alike.
It is flounder season. Whether you prefer to catch your own or buy from the local seafood market I think will enjoy one of the variety of ways to prepare this fish.
A flounder scurrying across the seafoor.
Photo: NOAA
Bay scallops (Argopecten irradians) have been an important part of the economy of many gulf coast communities within the Florida Big Bend for decades. It was once abundant in all gulf coast counties of the state but beginning in the 1960s populations in many bays began to decline to levels where they are all but nonexistent. The cause of this decline has been associated with many factors including a decline in water quality, a decline in suitable habitat (sea turtle grass beds – Thalassia), and overharvesting. Most likely the cause included all of these. Since the collapse of both the commercial and recreational fishery, Gulf coast communities have been trying to address all three of the stressors above. Multiple monitoring projects are ongoing in the Pensacola Bay area and one of those is the Great Scallop Search.
The Great Scallop Search was developed by Sea Grant Agents in Southwest Florida and expanded, through Florida Sea Grant, to Northwest Florida. In each location volunteers snorkel a 50-meter transect line searching for live bay scallops, as well as monitoring the status of the seagrass habitat. Since 2015 317 volunteers have logged 634 hours surveying 407 50-meter transects in 106 grids in Big Lagoon or Santa Rosa Sound. In that time 4 live scallops have been logged, though we hear anecdotal reports of additional scallops being found in these bodies of water.
Survey Method
Volunteers select and survey one of 11 grids in Big Lagoon, or one of 55 grids in Santa Rosa Sound. Once on site, the volunteers anchor and record preliminary information on the data sheet provided. Two snorkelers enter the water and swim on opposite sides of a 50-meter transect line searching for live scallops. Any live scallop found is measured and returned. The species and density of the seagrass is recorded as well as the presence/absence of macroalgae on that seagrass. Four such transects are surveyed in each grid.
2023 Results
2023
SRS
BL
Total
Other
# of volunteers
72
No significant difference between 2022 and 2023
# of grids surveyed
8
8
16
Slight decrease from 2022. 16 of the 66 grids (24%) were surveyed.
# of transects surveyed
26
51
77
A decrease from 2022. More surveys were conducted in Big Lagoon than Santa Rosa Sound.
Area surveyed (m2)
2600
5100
7700
1.9 acres
# of scallop found
2
2
4
Four live scallops are a record for this project. It equals the sum of all other live scallops since the project began.
Scallop Size (cm)
4.5, 5.0
4.0, 4.5
Surveys with Seagrass
Halodule
5
12
17
17/21 surveys – 81%
Thalassia
8
11
19
19/21 surveys – 90%
Syringodium
0
2
2
2/21 surveys – 10%
Grass Density
100% grass
3
9
12
12/21 surveys (57%) were 100% grass
90%
1
0
1
Note: Volunteers typically select area for transects
75%
3
1
4
with a lot of grass.
70%
1
0
1
50%
3
9
12
5%
1
0
1
Macroalgae
Present
4
4
8
Absent
2
10
12
12/21 surveys (57%) had no macroalgae.
Abundant
2
2
4
Sediment Type
Mud
0
1
1
Sand
7
8
15
15/21 surveys (71%) were sandy.
Mixed
1
4
5
21 surveys were conducted covering 16 grids. 8 grids were surveyed in each body of water.
A total of 77 transects were conducted covering 7,700 m2 and four live scallops were found.
Two of the scallops were found in Big Lagoon and two in Santa Rosa Sound.
All scallops measured between 4-5cm (1.6-2”).
The number of live scallops found this year equaled the total number found over the last eight years.
Most of the transects included a mix of Halodule and Thalassia seagrass ranging from 100% coverage to 5%. The majority of the transects were between 50-100% grass. Four transects had 100% Thalassia. Three of those were in Santa Rosa Sound, one was in Big Lagoon. The diving depth of the volunteers ranged from 0 meters (0 feet) to 2.4 meters (8 feet). Macroalgae was present in 8 of the 21 surveys (38%) but was not abundant in most.
Volunteer measuring one of the four collected bay scallops in 2023 from Pensacola Bay.
Photo: Gina Hertz.
Summary of Project
Year
Volunteer
Grids Surveyed
Transects Surveyed
Live Scallops Found
2015
87
28
101
0
2016
96
31
111
1
2017
5
4
16
0
2018
20
7
32
0
2019
13
6
20
0
2020
5
2
16
1
2021
17
6
24
0
2022
74
22
87
2
2023
72
16
77
4
TOTAL
317
407
8
MEAN
35
14
45
0.4
To date we are averaging 35 volunteers each event, surveying 14 of the 55 possible grids (25%). We are averaging 45 transects each year (4500 m2), have logged 407 transects (40,700 m2) and have recorded 8 live scallops (< than one a year).
Discussion
Based on the results since 2016 this year was a record year for live scallops. Whether they are coming back on their own is still to be seen. Being mass spawners, bay scallop need high densities in order to reproduce successfully, and these numbers do not support that. The data, and comments from volunteers, suggest that the grasses look good and dense. Thalassia, a favorite of the bay scallop, appear to be becoming more abundant. This is a good sign.
Though small and few, bay scallops are trying to hold on in Pensacola Bay.
Photo: Gina Hertz
You might say this is a strange title – “meet the barnacle” – because everyone knows what a barnacle is… or do they?
As a marine science instructor, I gave my students what is called a lab practical. This is a test where you move around the room and answer questions about different creatures preserved in jars. Almost every time that got to the barnacle they were stumped. I mean they knew it was a barnacle but what kind of animal is it? What phylum is it in?
Going through a thought process they would more often than not choose that it was a mollusk. This makes perfect sense because of the calcium carbonate shell it produces. As a matter of fact, science thought it was a mollusk until 1830 when the larval stage was discovered, and they knew they were dealing with something different. It is not a mollusk. So… what IS it? Let’s meet the barnacle…
Barnacles along the seashore is a common site for many.
Photo: NOAA
The barnacle is actually an arthropod. Yep… the same group as crabs and shrimp, insects and spiders. Weird right…
But that is because the creature down within that calcium carbonate shell is more like a tiny shrimp than an oyster. It is in the class Cirripedia within the subphylum Crustacea. It is the only animal in this class and the only sessile (non-motile) crustacean.
Barnacles are exclusively marine. This has been helpful when conducting surveys for terrapins or assessing locations for living shorelines – if you see barnacles growing on rocks, shells, or pilings, it is salty enough. There are over 900 species described and they live independently from each other attached to seawalls, rocks, pilings, boats, even turtle shells. Louis Agassiz described the barnacle as “nothing more than a little shrimplike creature, standing on its head in a limestone house kicking food into its mouth.”
This image from a textbook shows the internal structure of a barnacle. Notice the shrimplike animal on its back with extendable appendages (cirri) for feeding.
Image: Robert Barnes Invertebrate Zoology.
The planktonic barnacle larva settles to the bottom and attaches to a hard substrate using a cement produced from a gland near the base of their first set of antenna (crustaceans, unlike insects and spiders, have two sets of antenna). It is usually head down/tail up and begins to secrete limestone plates forming the well known “shell” of the animal. Some barnacles produce a long stalk near the head end (called the peduncle) which holds the adhesive gland and it is the peduncle that attaches to the hard substrate, not the head directly. The goose neck barnacle is an example of this. We find them most often in the wrack along the Gulf side of our beaches attached to driftwood or marine debris.
Lucky was found in the Gulf of Mexico. He had been there long enough for these goose neck barnacles to attach and grow.
Photo: Bob Blais
The “shell” of the barnacle is a series of calcium carbonate plates they secrete. These plates overlap and are connected by either a membrane or interlocking “teeth”. The body lies 90° from the point of attachment on its back.
There are six pairs of “legs” which are very long and are extended out of the “doors” of the shell and make a sweeping motion to collect planktonic food in the water column. They are most abundant in the intertidal areas were there are rocks, seawalls, or pilings.
Most species are hermaphroditic (possessing both sperm and egg) but cross fertilization is generally the rule. Barnacles signal whether they are acting males or females via pheromones and fertilization occurs internally, the gametes are not discharged into the water column as in some mollusks and corals. The developing eggs brood internally as well. Our local barnacle (Balanus) breeds in the fall and the larva (nauplius) are released into the water column in the spring by the tens of thousands. The larva goes through a series of metamorphic changes until it settles on a hard substrate and becomes the adult we know. They usually settle in dense groups in order to enhance internal fertilization for the next generation. Those who survive the early stages of life will live between two and six years.
So, there you go… this is what a barnacle is… a shrimplike crustacean who is attached to the bottom by its head, secretes a fortress of calcium carbonate plates around itself, and feeds on plankton with its long extending legs. A pretty cool creature.
Reference
Barnes, R.D. 1980. Invertebrate Zoology. Saunders College Publishing. Philadelphia PA. pp. 1089.
There is a term that all oyster farmers dislike, it is almost like that one villain from a famous book/movie series where they shouldn’t say his name. That term is “unexplained spring/summer mortality” and it has been a growing issue along with the expansion of oyster farming throughout the southeast. While the art of oyster farming has been around since the time of the Romans, it is a relatively new venture here in the Gulf of Mexico, and Florida is home to over one hundred oyster farms. These farms are meticulously cared for by the oyster farm crew, with many different anti-fouling techniques and biosecurity measures in practice to provide the customer with a safe, clean product that you can consume even in the months without an R (another article on that coming later). Each year, farm managers can expect a 10-30% mortality event during the transition from winter into spring/summer, hence the term “unexplained spring/summer mortality.” Researchers and scientists from all over the southeast have been actively working to find a cause for this phenomenon, but the answer has been hard to find.
Dead, market ready oysters from one bag. Cause of death, “Unexplained Mortality Event 2022” Photo by: Thomas Derbes II
Our Pensacola Bay has been a hotbed for oysters lately; The Nature Conservancy recently constructed 33 oyster beds along Escribano Point in East Bay, the establishment of the Pensacola & Perdido Bay Estuary Program, acquisition of a $23 million restoration grant with $ 10 million towards 1,482 acres of oyster restoration, and the establishment of oyster farms and hatcheries. In Pensacola Bay, there are currently 5 oyster farms in operation, one of those farms being a family-owned and operated Grayson Bay Oyster Company. Brandon Smith has been managing the business and farm for over 4 years now and has experienced mortality events during those prime spring/summer months. In recent years, they have experienced mortality events ranging from minimal to what many would consider “catastrophic,” and reports from around Florida and the Southeast convey a similar message. Concerned for not only the future of his family farm, but other oyster farms in the Southeast, he has been working with the most experienced institutions and groups in 2022 to possibly get an answer on his and other local “unexplained mortality events.” Each road led to the same answer of “we aren’t quite sure,” but this didn’t deter Smith or other the farmers who are dealing with similar issues.
In 2023, Smith was invited to participate in a Florida-Wide program to track water quality on their farm. This project, led by Florida Sea Grant’s Leslie Sturmer from the Nature Coast Biological Station in Cedar Key, Florida, hopes to shed some light on the changes in water quality during the transition from winter to spring and spring to summer. Water samples have also been taken weekly to preserve plankton abundance and the presence of any harmful algae if a mortality event does occur. With the hottest July on record occurring in 2023, temperature could play a role in mortality events, and now researchers are equipped with the right tools and open lines of communication to possibly find a solution to the problem.
3-month-old seed being deployed out on Grayson Bay Oyster Company’s farm in Pensacola, Florida (2023). Photo by: Thomas Derbes II
As with traditional farming on land, oyster farming takes a mentally strong individual with an incredible work ethic and the ability to adapt to change. The Southeast has a resilient system of oyster farmers who display these traits and continue to put their noses down and “plant” seed every year for the continuation of a growing yet small industry, even through the hardest of trials and tribulations. Through collaboration with local and state institutions, stakeholders, programs, and citizens, oyster farmers are hopeful that they can solve this “unexplained mortality event” and help develop resilient farming techniques. An important message is local farms that have environmental and economic impacts cannot exist without the support of their community.
If you’re interested in tracking water quality on select farms, including Grayson Bay Oyster Company, the website is https://shellfish.ifas.ufl.edu/farms-2023/ and it is updated monthly.
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.
