In the final segment of this 3 part series on worms we will discuss the largest, most commonly encountered members of the worm world… the Annelids.
Neredia are one of the more common polychaete worms. Photo: University of California Berkley
Annelids differ from the other two groups of worms we have discussed in that they have segmented bodies. They are largest of the worms and the most anatomically complexed. The fluids of their coelomic cavity serve as a skeleton which supports muscle movement and increases locomotion. The annelids include marine forms called Polychaetes, the earthworms, and the leeches.
POLYCHAETES
Polychaetes are the most diverse group of annelids and most live in the marine environment. They differ from earthworms and leeches in that they have appendages called parapodia and do not possess a clitellum. In size they range from 1 mm (0.04”) to 3 m (10’) but most are around 10 cm (4”). Many species display beautiful coloration and some possess toxic spines.
There are 3 basic life forms of polychaetes; free-swimming, sedentary, and boring. The free-swimming polychaetes are found swimming in the water column, crawling across the seabed, or burrowing beneath the sediments. Some species are responsible for the “volcanoes” people see when exploring the bottom of our local bays. Most sedentary polychaetes produce tubes within which they live. Some tubes are made of elastic organic material and others are hard, stony, and calcareous. “Tubeworms” rarely leave their tubes but extend appendages from the tube to collect their food. Most feed on organic material either in the water column or on the seabed but some species collect and consume small invertebrates. There are commensal polychaetes but parasitism is rare. All polychaetes have gills and a closed circulatory system and some have a small heart. As with the other Annelids, polychaetes do have a small brain and are aware of light, touch, and smell; most species dislike light. Reproduction involves males and females who release their gametes in the water where fertilization occurs and drifting larva form.
The tube of a common tubeworm found on panhandle beaches; Diopatra. Photo: University of Michigan
EARTHWORMS
Aside from parasitic tapeworms and leeches, earthworms are one of the more commonly recognized varieties of worms. Many folks actually raise earthworms for their gardens or for fish bait; a process known as vermiculture. Earthworms differ from polychaetes in that they do not have parapodia but DO possess a clitellum, which is used in reproduction. Though most live in the upper layers of the soil there are freshwater species within this group. They are found in all soils, except those in deserts, and can number over 700 individuals / m2. The number of earthworms within the soil is dependent on several factures including the amount of organic matter, the amount of moisture, soil texture, and soil pH. Scientists are not sure why earthworms surface during heavy rains but it has been suggested that the heavy drops hitting the ground can generate vibrations similar to those of an approaching mole; a reason many think “fiddling” for worms works. Earthworms can significantly improve soil conditions by consuming soil and adding organics via their waste, or castings. Unlike polychaetes, earthworms lack gills and take in oxygen through their skin, one reason why they most live in moist soils. Another difference between them and polychaetes is in reproduction. Aquatic polychaetes can release their gametes into the water where they are fertilized but terrestrial earthworms cannot do this. Instead two worms will entangle and exchange gametes; there are no male and females in this group. The fertilized eggs are encased in a mucous cocoon secreted by the clitellum.
LEECHES
Here is another creepy worm… leeches. Leeches are segmented, and thus annelids, and like earthworms they lack the parapodia found in polychaetes and possess a clitellum for reproduction. Most leeches are quite small, 5 cm (2”) but there is one from the Amazon that reaches 30 cm (12”). Most are very colorful and mimic items within the water, such as leaves. They differ from earthworms in that they are flatter and actually lack a complete coelomic cavity; which most annelids do have. They also possess “suckers” at the head and tail ends.
The ectoparasite we all call the leech. Photo: University of Michigan
Leeches prefer calm, shallow water but are not fans low pH tannic rivers. If conditions are favorable their numbers can be quite high, as many as 10,000 / m2. They are found worldwide but are more common in the northern temperate zones of the planet; North America and Europe.
Some species feed by using an extending proboscis which they insert and remove body fluids, but most actually have jaws with teeth and use them to rip flesh to cause bleeding, cutting as frequently as 2 slices/second. Those with teeth possess an anesthesia that numbs the area where the bite occurs. Both those with and without teeth possess hirudin, which is an anticoagulant, allowing free-bleeding until the worm is full. Those who feed on blood tend to prey on vertebrates and most species are specific to a particular type of vertebrate. It is known they can detect the smell of a human and will actually swim towards one who is standing still in the water. It takes several hundred days for a leech to digest a full meal of blood and so they feed only once or twice a year. They remove most of the water from the blood once they swallow and require the assistance of bacteria in their guts to breakdown the proteins. They can detect day and night, and prefer to hide from the light. However when it is feeding time they are actually attracted to daylight to increase their chance of finding a host. Vibrations, scent, even water temperature (signaling the presence of warm blooded animals) can stimulate a leech to move towards a potential prey. Leeches, like earthworms, reproduce using a clitellum and develop a cocoon.
Though most find worms a disgusting group of creatures to be avoided, they are actually very successful animals and many species are beneficial to our environment. We hope you learned something from this series and will try and learn more.
For locals along the coast ghost crabs are as common as mockingbirds and mourning doves. Before Ivan, when the dunes were larger and closer to the road, viewing the white crabs scouring across the road at night in your headlights forced all into defensive driving maneuvers. And for those who have ever tried to catch one, all would agree it is one of the fastest animals on the beach.
The common ghost crab. Photo: Virginia Institute of Marine Sciences
Ghost crabs (Ocypode quadrata) are members of the fiddler crab family. Like their fiddler crab cousins, they are more terrestrial than aquatic and dig burrows to protect themselves from predators and the intense heat of the midday sun. Though ghost crabs can be found in a variety of locations on the island, they are most frequently found between the mean high tide line and the upper portions of the primary dune line; typically on the Gulf side. Their “J” shaped burrows reach the water level below the sand and can run as deep as four feet. Larger individuals can dig deeper burrows and are often found further away from the water’s edge. These are crabs and thus still possess gills. Gills must be in contact with water in order to obtain needed oxygen. To do this ghost crabs have a gill chamber that will hold water for periods of time. The crabs can obtain water either at the bottom of their burrow or by running to the edge of the Gulf. And running is a good term for what they do. Once they have left the burrow they will lift five of their 10 legs above their head running on the remaining five. Running sideways they will have three in contact with ground in the direction they are going and two on the opposite side; if you look closely you can actually the remaining legs raised high in the air. When they tire, they will stop, make a 180° turn, and begin running again; resting their legs. They have reached speeds of 1.6 meters/second, which is 3.5 mph!
Ghost crabs are most active at night, though they are found at dawn and dusk and occasionally at midday. They feed on invertebrates at the surface zone such as mole crabs (sand fleas) and coquinas (bean clams). Dead fish and other animals found along the shoreline are also part of their diet, often dragging them back to their burrow. Unfortunately they are one of the predators of sea turtle hatchlings heading to the Gulf at night. Ghost crabs breed in late spring and early fall. The females will carry her developed eggs to the surf zone to release them. The developing young will return the following spring to mate and release their own eggs. Females may produce eggs in their second year but rarely live to do the same the third year. They are quite social with other crabs communicating, like their fiddler crab cousins, with body postures and claw movements. They are most active from March to December, plugging the entrance of their burrows and going dormant during the colder months of the year.
There has been concern about the impact of the oil spill on their numbers and the numbers of their prey, mole crabs and coquina. Our beaches did have small and large patches of oil that seeped down into the sand and then there were the methods used to remove the oil from the beach. At this point we do not know how hard their populations were impacted but scientists have collected data before and after the spill and are analyzing this now. However low their population dropped I am sure these resilient creatures will rebound and we will once again dodge them during our evening drives.
A room with a view: a stripped hermit crab sizes up a potential residence
Summertime in north Florida is good. Among the premium experiences are leisurely hours at the beach.
For many this is a period of relaxation and the opportunity to casually examine what the surf has thrown on the beach. It can be the culmination of a summer vacation or a weekend reprieve from the contemporary insanity of 2015’s workaday grind.
The hermit crab is one commonly encountered native creature which is slow-moving and hard to miss observing. It scuttles along the shallow coastal waters in search of its immediate needs.
In most cases it is the next meal which prompts this member of the Pagurus genus to fitfully crawl about in the borrowed disguise of a gastropod. They are not particular which shell they occupy just so long as it fits their size and is transportable.
Likewise, they are not especially particular about their meals. Hermit crabs are omnivores which relentlessly scavenge for anything digestible in the shallow waters of much of the world.
Their family includes about 1100 members which differ in size, color and housing choices. Some, in other regions, will even lodge in immovable locations and depend on the tidal currents to provide for their nutritional requirements.
When times are good and the hermit crab has plenty to eat, it will outgrow it’s the shell which fate provided for its use. The search for a replacement requires probing, luck and can produce aggressive behavior between hermit crabs if appropriately sized shells are in short supply.
Without the shell a hermit crab is an easy meal for other denizens of the deep. If the shell is too small, the hermit crab cannot grow properly or withdraw into the shell completely which exposes it to the unending stream of predators.
The upper portion of their bodies is covered with a hard exoskeleton, but their abdomen is soft and vulnerable to attack. The long and pliable abdomen is useful for firmly holding to a vacant snail shell which provides the necessary protection.
The technique has proven very successful for the hermit crabs as a whole. Fossil records indicate these crustaceans have existed since the last days of the dinosaurs.
While hermit crabs live alone in the shells they procure, they are commonly found in colonies and compete for a variety of necessary resources and mates. Their collective activity has attracted the attention of many young beach goers.
The small, shy creatures have held unending fascination for generations of children. The hide and seek nature of their behavior retreating into shells at the first appearance of a threat increases the enticement.
The temptation to return home with a unique and diminutive pet has proven irresistible for many. One can only guess how many parents have first learned of their child’s decision by the aroma of a deceased hermit crab.
It is a good thing the visit to the beach is relaxing. To learn more about hermit crabs contact the nearest UF/IFAS Extension Office.
Pregnant Bull Shark (Carcharhinus leucas) cruses the sandy seafloor. Credit Florida Sea Grant Stock Photo
Shark Safety Tips
UF/IFAS Extension – Florida Sea Grant
By L. Scott Jackson (Bay County) and Rick O’Connor (Escambia County)
Recently, two teens were victims of unusual shark attacks in North Carolina. The two attacks occurred within minutes and miles of each other. A similar incident happened in the Florida Panhandle in 2005. One teen lost her life and one lost his leg. The attacks were within days of each other and the distance between the two attacks was less than 100 miles. Experts identified Bull Sharks as being responsible for both Panhandle shark encounters.
Bull Sharks migrate north as ocean waters of the Gulf and Atlantic warm. As the nearshore environment cools in the late fall and winter, Bull Sharks follow the receding warm water and eventually move out of the local area. Bull Sharks are an aggressive shark responsible for a reported 100 attacks on humans resulting in 21 fatalities. (Reported from 1580 to 2014 Source: International Shark Attack Files).
Experts suggest Bull Sharks may be responsible for many shark attacks where the species is unknown or not identified.
Overall, the number of shark encounters is slowly trending higher as more people swim and participate in other water related activities. However, negativeencounters with sharks remain a rare occurrence. In 2014, Florida reported 28 shark bites with no fatalities. On average, only one shark attack fatality is reported every other year in the United States. The risk of shark attack is very low compared to other potential recreational hazards. For example, in 2014, 26 people died as a result of lightning strikes in the United States, with six of those being in Florida.
George Burgess with the International Shark Attack File has compiled a list of action strategies you can use to reduce the chances of a negative encounter with a shark:
Keep these tips in mind the next time you hit the beach!
Avoid being in the water from sunset to sunrise. This is when sharks are most active and have a competitive sensory advantage.
Stay in a group, and do not wander too far from shore. Isolated individuals are more likely to be attacked than large groups; in addition, the farther you are from shore, the farther you are from help.
Consider your clothing: avoid wearing shiny jewelry, because the reflected light resembles the sheen of fish scales.
Avoid brightly colored or patterned clothing, because sharks see contrast particularly well.
Do not enter waters being used by sport or commercial fisherman – sharks can sense the smells emitted from bait at incredible distances.
Avoid entering waters with sewage output and/or entering the water if you are bleeding. Such additions to the water can act as strong olfactory attractants to sharks.
Know your facts! Porpoise sightings do not indicate the absence of sharks. In fact, the opposite is often true. Also be on the lookout for signs of baitfish or feeding activity – diving seabirds are good indicators of such action. Animals that eat the same food items are often found in close proximity. Remember, a predator is never too far from its prey.
Refrain from excess splashing while in the water, and do not allow pets in the water because of their erratic movements.
Exercise caution when occupying the area between sandbars or near steep drop-offs, as these are favorite hangouts for sharks.
Do not enter the water if sharks are known to be present, and evacuate the water if sharks are seen while there. And, of course, do not harass a shark if you see one!
Stay calm if you do see a shark, and maintain your position in as quiet a manner as possible. Most sharks merely are curious and will leave on their own.
Our beautiful Emerald Coast is an alluring wild habitat. Simply put – Swimming at the beach is not the same as swimming in a backyard pool. Have fun at the beach but be mindful and respectful of potential hazards. Knowing what to do to be safe will actually help you enjoy time at the beach while keeping worry and concern at a minimum.
Follow these beach safety tips for helping your family enjoy the beach while protecting coastal wildlife.
For many who are seafood lovers there is nothing like a good grouper sandwich; makes me hungry just to write that. Groupers are members of the one of the largest families of fish in the Gulf of Mexico. There are 33 species in the family Serranidae, which include sea bass and perch, and many are sold as “grouper” in the seafood markets. There are 10 species of searranids that are in the genus Epinephelus and are considered the true groupers. One of these, Epinephelus itajara , is a monster; this is the Goliath Grouper.
Three goliath groupers over wreck in southwest Florida. Photo: Bryan Fluech Florida Sea Grant
As the name states, these fish can reach 6 feet in length and over 700 lbs. Goliath groupersare generally found on structure such as artificial reefs, near drill platforms, and on natural bottom. They tend to stay near the reefs they inhabit but will travel long distances for breeding. Data suggest that the highest concentrations of these fish are in southwest Florida but they disperse across the Gulf and along the Atlantic coast of south Florida. The large spawning aggregations occur offshore, generally from July through September, and the planktonic larva drift into the mangrove estuaries of southwest Florida. Here the young fish live for 5-6 years feeding on the abundance of food found there and then head back offshore searching for reefs to call their own. Many head to the northern Gulf and our area. Though they are large they feed relatively low on the food chain, consuming primarily crustaceans and slow moving reef fish.
They were a huge trophy fish back in the middle 20th century. Fishermen could not resist the chance to have a photograph with one of these behemoths. Because of this popular activity, and the loss of their mangrove nursery grounds due to development, their numbers diminished across the state and today there is a “no harvest” rule for the fish. However some divers are indicating their numbers are increasing and that the Florida Fish and Wildlife Conservation Commission should to revisit the rule.
In response FWC’s research group, Fish and Wildlife Research Institute, in St. Petersburg conducts an annual “Goliath Grouper Count”. Modeled after the Christmas Bird Count conducted each year by the Audubon Society, the Goliath Grouper Count occurs during the first week of June. The counts have been occurring in south Florida for a couple of years but for the first time the panhandle will be participating this year. If you are a diver and interested there is a particular protocol that needs to be followed when counting. You can find out more by contacting Rick O’Connor in Pensacola at (850) 475-5230 or Scott Jackson in Panama City at (850) 764-6105 to obtain the protocol and the data sheets. The official count will run between June 1 and June 15.
Life Stages of the True Jellyfish: Photo: By Matthias Jacob Schleiden (1804-1881) [Public domain], via Wikimedia Commons
“Ouch, something just stung me.” This is a common phrase to hear someone say (I’ve heard myself say it) while enjoying the otherwise soothing waters along our beautiful Gulf Coast. We host an amazing variety of marine organisms that possess the ability to sting when contacted. I’m referring to organisms in the phylum Cnidaria (pronounced “ni-dair-ee-ah”), which includes about 10,000 species that have been identified. There is general agreement on the classification of five different classes of cnidarians, all of which have stinging cells, but most of which are not dangerous to humans. These include Class Anthozoa (anemones and corals), Class Cubozoa (box jellyfish), Class Scyphozoa (true jellyfish), Class Staurozoa (stalked jellyfish) and Class Hydrozoa (hydroids i.e. Portuguese man o’ war). I’m always intrigued by the origin of scientific names so here is a slight tangent for you on the group names (Cnides: from the greek meaning nettle)(Antho: flower-like; Cubo: cube-shaped; Scypho: cup-shaped; Hydros: sea serpent; Stauro: cross-shaped). The term “zoa,” of course, refers to animals.
Most of the time you are stung in our local waters it involves the classes Hydrozoa or Scyphozoa. The Hydrozoans are a complex group of organisms but most species go through two distinct stages during their life cycle. The hydroid stage takes the form of a polyp which is composed of a stalk and tentacles at the end. Polyps can be single but are often colonial, connected by tube-like structures. Most polyps are specialized for feeding but others are used to reproduce. Reproductive polyps lack tentacles but have many buds which form the medusa stage of the organism for reproduction purposes. Medusae of the hydroids are similar in design but typically smaller than the medusae of the true jellyfish. Some hydroids also have specialized defensive polyps with numerous stinging cells and one species even has a specialized polyp that develops into a large balloon-like float that the others attach to (the man o’ war). There is one specific type of hydroid in our area that closely resembles a piece of branching brown algae, such as Sargassum. The polyps are scattered along the branches and when brushed against they fire their nematocysts (stinging cells) producing a painful sting. The burning sensation can last for several minutes and you would have sworn the only thing around you was a harmless piece of drift algae.
The true jellyfish, of Class Scyphozoa, also go through a polyp and medusa stage. The polyps of this class are typically single and settle to the bottom as larvae and attach themselves. Over time the polyps mature and produce other polyps by budding, or bud medusae off their upper surface. These jellyfish medusae are microscopic at this stage and many take years to reach maturity, complete with a cup-shaped (scypho= cup shaped) bell and tentacles hanging beneath.
The subsequent lives of these translucent marine creatures is no less intriguing than the processes involved in their development. Check out this website from the Smithsonian for more great information. The next time you feel the burn of a host of nematocysts injecting you with their potent venom, I dare you to stop for just a second to be amazed by the fascinating creature that you have just met. If you can pull this off you are well on your way to becoming the quintessential nature nut! Click here for helpful information if you are stung.
