The WFSU Ecology Blog
  • Home
    • About
    • EcoAdventures
      • Kayak and Canoe Adventures
      • Hiking
      • Wildlife Watching
    • Observations From the Field
      • White Pelicans Visit Dr. Charles L. Evans Pond in Tallahassee
      • An April Walk at Ochlockonee River WMA
      • Nesting Raptors at Honeymoon Island State Park
    • WFSU Public Media Home
  • Documentaries
    • In Their Words: Black Legacy Communities in North Florida
    • EcoCitizen Show | Seasons in South Tallahassee
    • Red Wolf Family Celebrates First Year at the Tallahassee Museum
    • Roaming the Red Hills
    • Oyster Doctors
    • Testing the Ecology of Fear
    • EcoShakespeare
    • Stories from the Apalachicola
    • Classic WFSU Ecology Documentaries
  • Habitats
    • Estuaries
      • Oyster Reef
        • The Effects of Predators and Fear on Oyster Reefs
        • Apalachicola Oyster Research
        • Animal Species in a North Florida Intertidal Oyster Reef
        • Oyster Reef Ecology | On the Reef
      • Salt Marsh
        • In the Grass- Salt Marsh Biodiversity Study
        • Plants and Animals of a North Florida Salt Marsh
        • Salt Marsh Ecology | In the Grass
      • Seagrass Bed
        • Predatory Snails, and Prey, of the Bay Mouth Bar Seagrass Beds
      • In the Grass, On the Reef Glossary
    • Waterways Big and Small
      • Aucilla/ Wacissa Watershed
      • Apalachicola Basin
        • Apalachicola Bluffs and Ravines | Virtual Field Trip
        • The Age of Nature Screening & Discussion | The Future of the Apalachicola
        • Apalachicola River and Bay
        • Apalachicola RiverTrek | Kayaking, Camping, & Hiking the River Basin
    • Longleaf Pine & Fire Ecology
  • Backyard Habitat
    • Backyard Blog
      • My Year in Bugs: the 2022 Backyard Blog
      • Backyard Ecology Blog | 2021
      • Backyard Blog November/ December 2020
      • Backyard Blog September/ October 2020
      • July and August 2020 Backyard Blog
      • Backyard Blog June 2020
      • Backyard Blog May 2020
      • Backyard Blog April 2020
      • Backyard Blog February and March 2020
      • Backyard Blog January 2020
      • Backyard Blog October through December 2019
      • Backyard Blog September 2019
      • Backyard Blog August 2019
      • Backyard Blog July 2019
      • Backyard Blog June 2019
      • Backyard Blog May 2019
      • Backyard Blog April 2019
      • Backyard Blog March 2019
      • Backyard Blog February 2019
      • Backyard Blog January 2019
      • The Backyard Bug Blog 2018
    • Backyard Flora and Fauna
      • Bees of North Florida and South Georgia
      • The Seasonality of Bees (and Bee Plants) in North Florida
      • Woody Vines of North Florida
      • Flies of North Florida are More Diverse than You’d Think
      • The Case for Weeds, Our Unsung Florida Native Plants
      • Devil’s Walkingstick: Your New Favorite Thorny Pollinator Plant?
      • Florida Native Milkweed | Tips for Growing Your Monarch Friendly Garden
      • Mistletoe | A Parasite for the Holidays (But Maybe We Like it Anyway?)
    • Florida Friendly Seasonal Planting Guide
    • Pollinator and Gardening Posts
    • Gardening Web Resources
Kayak and Canoe Adventures
RiverTrek 2021: Five Days on the Apalachicola River
Lower Lake Lafayette: Kayak Tallahassee’s Hidden Swamp
Chipola River Paddling Trail | The Ovens and...
Kayaking Bald Point | Adventure on a Living...
Wacissa Springs Adventure | Kayaking a Wild Florida...
A Geologist’s View of the Apalachicola River |...
Upper Chipola River Kayak Adventure | Ghosts &...
Tate’s Hell & the Apalachicola River Delta |...
Kayak Scouting Mission on the Ochlockonee Water Trail
Merritt’s Mill Pond | Kayaking and Spring Caves

The WFSU Ecology Blog

  • Home
    • About
    • EcoAdventures
      • Kayak and Canoe Adventures
      • Hiking
      • Wildlife Watching
    • Observations From the Field
      • White Pelicans Visit Dr. Charles L. Evans Pond in Tallahassee
      • An April Walk at Ochlockonee River WMA
      • Nesting Raptors at Honeymoon Island State Park
    • WFSU Public Media Home
  • Documentaries
    • In Their Words: Black Legacy Communities in North Florida
    • EcoCitizen Show | Seasons in South Tallahassee
    • Red Wolf Family Celebrates First Year at the Tallahassee Museum
    • Roaming the Red Hills
    • Oyster Doctors
    • Testing the Ecology of Fear
    • EcoShakespeare
    • Stories from the Apalachicola
    • Classic WFSU Ecology Documentaries
  • Habitats
    • Estuaries
      • Oyster Reef
        • The Effects of Predators and Fear on Oyster Reefs
        • Apalachicola Oyster Research
        • Animal Species in a North Florida Intertidal Oyster Reef
        • Oyster Reef Ecology | On the Reef
      • Salt Marsh
        • In the Grass- Salt Marsh Biodiversity Study
        • Plants and Animals of a North Florida Salt Marsh
        • Salt Marsh Ecology | In the Grass
      • Seagrass Bed
        • Predatory Snails, and Prey, of the Bay Mouth Bar Seagrass Beds
      • In the Grass, On the Reef Glossary
    • Waterways Big and Small
      • Aucilla/ Wacissa Watershed
      • Apalachicola Basin
        • Apalachicola Bluffs and Ravines | Virtual Field Trip
        • The Age of Nature Screening & Discussion | The Future of the Apalachicola
        • Apalachicola River and Bay
        • Apalachicola RiverTrek | Kayaking, Camping, & Hiking the River Basin
    • Longleaf Pine & Fire Ecology
  • Backyard Habitat
    • Backyard Blog
      • My Year in Bugs: the 2022 Backyard Blog
      • Backyard Ecology Blog | 2021
      • Backyard Blog November/ December 2020
      • Backyard Blog September/ October 2020
      • July and August 2020 Backyard Blog
      • Backyard Blog June 2020
      • Backyard Blog May 2020
      • Backyard Blog April 2020
      • Backyard Blog February and March 2020
      • Backyard Blog January 2020
      • Backyard Blog October through December 2019
      • Backyard Blog September 2019
      • Backyard Blog August 2019
      • Backyard Blog July 2019
      • Backyard Blog June 2019
      • Backyard Blog May 2019
      • Backyard Blog April 2019
      • Backyard Blog March 2019
      • Backyard Blog February 2019
      • Backyard Blog January 2019
      • The Backyard Bug Blog 2018
    • Backyard Flora and Fauna
      • Bees of North Florida and South Georgia
      • The Seasonality of Bees (and Bee Plants) in North Florida
      • Woody Vines of North Florida
      • Flies of North Florida are More Diverse than You’d Think
      • The Case for Weeds, Our Unsung Florida Native Plants
      • Devil’s Walkingstick: Your New Favorite Thorny Pollinator Plant?
      • Florida Native Milkweed | Tips for Growing Your Monarch Friendly Garden
      • Mistletoe | A Parasite for the Holidays (But Maybe We Like it Anyway?)
    • Florida Friendly Seasonal Planting Guide
    • Pollinator and Gardening Posts
    • Gardening Web Resources

Predatory Snails, and Prey, of the Bay Mouth Bar Seagrass Beds

by Rob Diaz de Villegas December 29, 2010
Predatory Snails, and Prey, of the Bay Mouth Bar Seagrass Beds
Click to subscribe to the WFSU Ecology Blog

Bay Mouth Bar is a series of sand bars and seagrass beds at the mouth of Alligator Harbor. For just a few days a month, the tide is low enough for it to be exposed for a couple of hours. When that happens, you can see an incredible diversity of life, including a higher diversity of predatory snails than anywhere else in the world. That’s what attracted Dr. Robert Paine to the area in the late 1950’s, as he was forming his ideas about keystone species and food webs. More recently, Dr. David Kimbro and his lab repeated surveys and found that there have been a few changes in the last fifty years. David’s doctoral student, Tanya Rogers, is conducting further research into whether the removal of one of Bay Mouth Bar’s top predators played a role in these changes.

In this Google Map, you can see the submerged sand off the tip of Alligator Point. During extreme low tides associated with full moons, much of this sand flat/ seagrass bed environment can become exposed.

Contents

  • Foundations Species- Seagrass species of Bay Mouth Bar
  • Top Predatory Snails
  • Other Predatory Snails
  • Other Snails
  • Bivalves
  • Other Invertebrates

Foundation Species

The beds at Bay Mouth Bar are made up of three different types of seagrass. Of interest to David and Tanya is the effect of predators on the grass. The larger predatory snails eat the smaller predators, who eat primarily clams and other bivalves. Those bivalves filter the water around the seagrass beds, taking nitrogen out of the water column and depositing in the sand, where the grasses make use of it. An imbalance in this relationship (such as the disappearance of a top predator species, such as the true tulip) might affect the clams, mussels, and scallops, which in turn might prevent nutrients from reaching the grasses.

Turtle grass (Thalassia testudinum)

Turtle Grass (Thalassia testudinum) in Saint Joseph Bay.
Turtle Grass (Thalassia testudinum) in Saint Joseph Bay.

Turtle grass is Florida’s most important seagrass species for habitat formation.  It derives its name from the sea turtles that eat it.  It is also eaten by several fish species and sea urchins.

Seagrass beds are one of the world’s most efficient carbon sinks. In the winter, turtle grass blades slough off, landing in mats along the shore called seagrass wrack.

Semipalmated plovers on seagrass wrack.
Semipalmated plovers on seagrass wrack at the Phipps Preserve on Alligator Point. Invertebrates in the wrack provide a valuable food source to shorebirds.

Shoal grass (Halodule wrightii)

Shoal grass on Bay Mouth Bar.
Shoal grass on Bay Mouth Bar.

Shoal grass is one of the dominant seagrass species in Florida. It is usually found growing in shallow water and can tolerate prolonged periods of exposure during low tide.

Manatee grass (Syringodium filiforme)

Lightning whelk in manatee grass, Saint Joseph Bay.
Lightning whelk in manatee grass, Saint Joseph Bay.

Manatee grass is commonly found in mixed seagrass beds.

Top Predators

When Dr. Paine surveyed Bay Mouth Bar in the 1950s, there were two top predators, depending on the season. For most of the year, this was and still is the horse conch. When the horse conch left for deeper waters in the winter, the true tulip (a species consumed by the horse conch) became to top predator. When David and his crew first surveyed the bar in 2011, however, they found that true tulips had disappeared.

Horse conch (Triplofusus giganteus)

Horse conch (Triplofusus giganteus) on shoal grass on Bay Mouth Bar.
Horse conch (Triplofusus giganteus) on shoal grass on Bay Mouth Bar.

Not a true conch, this large snail is a predator in the lower intertidal and subtidal zones. It feeds on other gastropods, such as lightning whelks and tulip snails, as well as pen shells.  The horse conch is the official state seashell of the state of Florida.

Horse conch eats lightning whelk on Bay Mouth Bar.
Horse conch eats lightning whelk on Bay Mouth Bar.

The horse conch is the largest predatory snail in Florida waters.  It places the bulk of its body on the operculum of the prey snail, preventing the prey from being able to withdraw inside its shell.  The horse conch then uses its relatively large proboscis to consume the prey’s flesh.

You may notice the multitude of organisms growing on the shell of the conchs at Bay Mouth Bar. These include barnacles, bryozoans, and oysters. For comparison, take a look at a horse conch from Saint Joseph Bay, which has no fresh water input from rivers. As a result, its water is clearer, and it lacks oysters and other organisms associated with sediment filled water:

  • Horse Conch (Triplofusus giganteus) in Saint Joseph Bay.
    Horse Conch (Triplofusus giganteus) in Saint Joseph Bay.
  • Horse conch on Bay Mouth Bar.
    Horse conch on Bay Mouth Bar.

As mentioned above, in the winter months, horse conchs leave Bay Mouth Bar for deeper waters. In November 2013, David and his crew spotted several mating pairs on the edge of the seagrass beds facing the gulf. Perhaps horse conchs mate before leaving, and lay their eggs in deeper waters?

Horse conchs mating on Bay Mouth Bay, November 2013.
Horse conchs mating on Bay Mouth Bay, November 2013.

Below is a young horse conch on a pen shell found in Saint Joseph Bay. These large bivalves are the only clams eaten by hose conchs.

Young horse conch snail on pen shell, Saint Joseph Bay.
Young horse conch snail on pen shell, Saint Joseph Bay.

Lastly, here is a photo with a mens size thirteen shoe next to a horse conch, for scale:

Horse conch (Triplofusus giganteus), next to size thirteen shoe for scale.
Horse conch (Triplofusus giganteus), next to size thirteen shoe for scale.

True tulip (Fasciolaria tulipa)

True tulip (Fasciolaria tulipa) eats a banded tulip (Cinctura lilium) at the FSU Coastal and Marine Lab.
True tulip (Fasciolaria tulipa) eats a banded tulip (Cinctura lilium) at the FSU Coastal and Marine Lab.

A predatory snail found in mud/ sand flats and seagrass beds. Tulips were once a primary predator of Bay Mouth Bar, but are no longer found in that community. As a top predator, these snails were second only to the horse conch, feeding on other snails and bivalves. The horse conch was its main predator on Bay Mouth Bar.

True Tulips are distinguished from Banded Tulips primarily by the lines on their shells. Adult Tulips have 25-38 interrupted lines along their shells, while Banded Tulips have 4-8 unbroken lines. Read more about an experiment being conducted by Tanya Rogers on the loss of predatory diversity on Bay Mouth Bar here.

Other Predatory Snails

These snails eat bivalves and smaller snails. As consumers of clams and mussels, they can influence how water is filtered around Bay Mouth Bar, and how nutrients are removed from the water column and deposited among the roots of seagrasses. Larger predators, such as hose conchs, play an important role in keeping these smaller predators in check, allowing bivalves to provide their ecosystem services.

Banded tulip (Cinctura lilium)

Banded tulip (Cinctura lilium) of the coast at Saint Teresa, Florida.
Banded tulip (Cinctura lilium) off the coast at Saint Teresa, Florida.

The Banded Tulip is a predator snail that feeds on a variety of prey including small snails, bivalves, tube worms, and carrion. True Tulips are distinguished from Banded Tulips primarily by the lines on their shells. Adult Tulips have 25-38 interrupted lines along their shells, while Banded Tulips have 4-8 unbroken lines.

Lightning whelk (Busycon perversum, Sinistrofulgur perversum)

Lightning whelk (Busycon perversum, Sinistrofulgur perversum) on a sand flat in Saint Joseph Bay,
Lightning whelk (Busycon perversum, Sinistrofulgur perversum) on a sand flat in Saint Joseph Bay,

Like the crown conch, the lightning whelk uses its proboscis to pry bivalves open and suck out the flesh.  Its proboscis is slender compared with that of a conch, and so it doesn’t have the force to pry open oyster shells, eating instead clams and mussels.  While they get fairly large compared to other predatory snails found in Florida waters, they do not consume other snails and are themselves consumed by tulip snails and horse conchs.

These whelks can be easily confused for knobbed whelks, with which it shares many characteristics. The best way to visually differentiate the two is by identifying on which side it curves.   Lightning whelks curve on the left (sinistral) side, knobbed whelks on the right (dextral).  This elegant curve gave the whelks particular value to Florida’s native Apalachee people and their counterparts in other Mississippian cultures. You can read more about whelks and the Apalachee here.

A lightning whelk engraved with a depiction of the Muscogee afterlife.
A lightning whelk engraved with a depiction of the Muscogee afterlife.

Muscogee culture is related to that of the Apalachee; hailing from nearby along the Chattahoochee River in Georgia and Alabama.  In 2018, we saw how Muscogee living in Tallahassee keep their culture alive, which includes the carving of medicine cups from lightning whelks.

Lightning whelk next to size thirteen shoe for scale.
Lightning whelk next to size thirteen shoe for scale. An older whelk, such as this one, is a filling meal for the only snail to grow larger than it in Florida waters- the horse conch.

Lace murex (Chicoreus florifer)

Lace murex (Chicoreus florifer)
Lace murex (Chicoreus florifer) snails. Tanya Rogers affixed hoops on these snails, by which they were tethered to seagrass beds on Bay Mouth Bar for an experiment.

The Murex is one of the predatory snails that has disappeared from Bay Mouth Bar. A drilling predator, the Murex is a specialist, feeding on bivalves, particularly cross-barred venus.

Read more about an experiment being conducted by Tanya Rogers on the loss of predatory diversity on Bay Mouth Bar here.

Pear Whelk (Busycotypus spiratus)

Pear Whelk (Busycotypus spiratus) on Bay Mouth Bar.
Pear Whelk (Busycotypus spiratus) on Bay Mouth Bar.

Pear whelks feed on bivalves and small snails, such as moon snails and turban snails.

White baby ear (Sinum perspectivum)

White Baby Ear (Sinum perspectivum) at Bay Mouth Bar.
White Baby Ear (Sinum perspectivum) at Bay Mouth Bar.

The White Baby Ear is a drilling predator that feeds on bivalves. Like the moon snail, the white baby ear burrows down into the sediment and can extend its body outside of its shell to nearly cover it. Unlike the moon snail though, it cannot completely retract its body inside its shell.

Atlantic moon snail (Neverita duplicata), also known as shark eye

Atlantic moon snail (Neverita duplicata), also known as shark eye, on a sand bar in Saint Teresa, Florida.
Atlantic moon snail (Neverita duplicata), also known as shark eye, on a sand bar in Saint Teresa, Florida.

Moon snails burrow in the sand flats, looking for its prey. Once its meal is found, the moon snail envelops it, secreting acid until the prey is soft enough for the snail to pierce with its radula. These snails are drilling predators and feed primarily on bivalves. The body of a moon snail can extend outside of its shell and almost completely cover it, but can be retracted completely inside when disturbed.

Atlantic moon snail feeding, its body extended out of its shell.
Atlantic moon snail feeding, its body extended out of its shell.

Other Gastropods (Snails)

Bruised nassa (Phrontis vibex)

Bruised nassa (Phrontis vibex)
Bruised nassa (Phrontis vibex)

These scavengers are generally known as “mud snails”. They have a long siphon with which they can smell food from long distances away.

Chestnut turban (Turbo cataneus)

Chestnut turban (Turbo cataneus)
Chestnut turban (Turbo cataneus), photo by Tanya Rogers.

Gulf oyster drill (Urosalpinx perrugata)

Common Atlantic Marginella (Prunum apicinum)

Bivalves

Ark clam (Andara sp.)

Ark clam (Andara sp.)
Ark clam (Andara sp.), photo by Tanya Rogers.

Bay scallop (Argopecten irradians)

Bay scallop (Argopecten irradians) in a Saint Joseph Bay seagrass bed.
Bay scallop (Argopecten irradians) in a Saint Joseph Bay seagrass bed.

Scalloping is a popular recreational activity in summer months, when scallops populations are sufficient to support the harvest. Check Florida Fish and Wildlife’s for current information on this year’s harvest in each gulf coast region.

In recent years, Saint Joseph Bay’s low scallop populations have cancelled or limited the recreational scallop seasons there. When they were more plentiful in 2014, we went in search of the tasty mollusks.

Bay Scallop with scallop spat, Saint Joseph Bay.
Bay Scallop with scallop spat, Saint Joseph Bay.

Broad-ribbed carditas (Cardites floridana)

Broad-ribbed carditas (Cardites floridana)
Broad-ribbed carditas (Cardites floridana), photo by Tanya Rogers.

Cross-barred Venus (Chione cancellata)

Cross-barred Venus (Chione cancellata)
Cross-barred Venus (Chione cancellata) on Bay Mouth Bar.

Florida prickly cockle (Trachycardium egmontianum)

Florida Prickly Cockle (Trachycardium egmontianum) at Bay Mouth Bar, off of Alligator Point.
Florida Prickly Cockle (Trachycardium egmontianum) at Bay Mouth Bar, off of Alligator Point.

Pen shell (Atrina sp.)

Pen shell in a Saint Joseph Bay seagrass bed.
Pen shell in a Saint Joseph Bay seagrass bed.

The largest clam on Bay Mouth Bar, it is the only bivalve consumed by horse conchs.

Southern horse mussel (Modiolus squamosus)

Southern horse mussel ( Modiolus squamosus)
Southern horse mussel (Modiolus squamosus), photo by Tanya Rogers.

Southern quahog (Mercenaria campechiensis)

Several cross barred venus clams inside of a quahog shell.
Several cross barred venus clams inside of a quahog shell.

Tanya Rogers tested the survivorship and causes of death of clams on Bay Mouth Bar by tethering baby quahog and sunray venus clams in various locations on the bar. Read more on Tanya’s experiment here.

Sunray venus (Macrocallista nimbosa)

Sunray venus (Macrocallista nimbosa) on Bay Mouth Bar.
Sunray venus (Macrocallista nimbosa) on Bay Mouth Bar.

Tanya Rogers tested the survivorship and causes of death of clams on Bay Mouth Bar by tethering baby quahog and sunray venus clams in various locations on the bar. Read more on Tanya’s experiment here.

Yellow egg cockle (Laevicardium mortoni), also known as Morton’s egg cockle

Yellow egg cockle (Laevicardium mortoni), also known as Morton's egg cockle
Yellow egg cockle (Laevicardium mortoni), also known as Morton’s egg cockle. Photo by Tanya Rogers.

Other Invertebrates

Keyhole sand dollar (Mellita quinquiesperforata), also known as five-slotted sand dollar

Keyhole sand dollar (Mellita quinquiesperforata), also known as five-slotted sand dollar.
Keyhole sand dollar (Mellita quinquiesperforata), also known as five-slotted sand dollar.

Sea urchin (phylum Echinodermata)

Sea Urchin on Bay Mouth Bar.
Sea Urchin on Bay Mouth Bar.

Spider crabs (Majoidea superfamily)

Spider crab in Saint Joseph Bay.
Spider crab in Saint Joseph Bay.

Tunicates (suphylum Tunicata)

Tunicate on the beach at St. Teresa, Florida.
Tunicate on the beach at St. Teresa, Florida.
Click to subscribe to the WFSU Ecology Blog


Facebook Comments
Share
FacebookTwitterRedditEmail

Search

Subscribe

Subscribe to receive more outdoor adventures, and an in depth look at our local forests and waterways by Email.

If you do not receive a verification e-mail, check your spam folder.

Category

WFSU-FM Environmental Stories

  • Tallahassee’s latest urban reforestation effort brings new trees to Governor’s Park
  • Hurricane Ian’s estimated damage to Florida agriculture tops $1B
  • America’s largest underground springs gets even bigger with the discovery of another cave connection
  • DeSantis outlines second-term environmental plans
  • Deep freeze breaks pipes, creates water crisis across South

Twitter

Tweets by wfsuIGOR

iNaturalist

iNaturalist became a part of the WFSU Ecology Blog during the EcoCitizen Project in 2019.  Since then, we’ve used it to help identify the many plants and animals we see on our shoots.  And on the Backyard Blog, we show how it can be used to identify weeds and garden insects, to help figure out what’s beneficial or a possible pest.  Below is the iNaturalist profile belonging to WFSU Ecology producer Rob Diaz de Villegas.

iNaturalist


View robdv’s observations »

Most Recent

  • The Wakulla Springs Wildlife Survey- a decades long look
  • Welcome Liesel Hamilton to the WFSU Ecology Blog!
  • My Year in Bugs: the 2022 Backyard Blog
  • Timberlane Ravine: learn to love dead trees (and trillium!)
  • The strange and dangerous love lives of zebra longwing butterflies

Archives

March 2023
M T W T F S S
 12345
6789101112
13141516171819
20212223242526
2728293031  
« Jan    

WFSU Ecology YouTube

  • Facebook
  • Twitter
  • Instagram
  • Flickr
  • Youtube

@2017 - PenciDesign. All Right Reserved. Designed and Developed by PenciDesign