Jellyfish Anemones Sea Cucumbers and Sea Pens

Jellyfish

Few marine creatures are as mysterious and intimidating as jellyfish. Though easily recognized, this animal is often misunderstood. Bathers and beachcombers react with fear upon encountering this invertebrate but, in fact, most jellyfish in South Carolina waters are harmless.

Jellyfish are members of the phylum Cnidaria. Members of this structurally simple marine group possess one of two body forms. Sea anemones, sea whips, corals and hydroids are polyps growing attached to rocks or other hard surfaces of the sea. Jellyfish and the Portuguese man-of- war are free-swimming medusae. Both body forms display radial symmetry with body parts radiating from a central axis. This symmetry allows jellyfish to respond to food or danger from any direction.

Instead of a brain, "true" jellyfish possess an elementary nervous system, or nerve net, which consists of receptors capable of detecting light, odor and other stimuli and coordinating appropriate responses.

Jellyfish are composed of an outer layer (epidermis) which covers the external body surface and an inner layer (gastrodermis) which lines the gut. Between the epidermis and gastrodermis is a layer of thick elastic jellylike substance called mesoglea ("middle jelly"). Jellyfish have a simple digestivecavity (coelenteron) which acts as a gullet, stomach and intestine with one opening for the mouth and anus. Four to eight oral arms are located near the mouth and are used to transport food that has been captured by the tentacles.

Jellyfish occur in a wide variety of sizes, shapes and colors. Most are semi-transparent or glassy and bell-shaped, measuring less than an inch to over a foot across the bell, although some may reach 7 feet. The tentacles of some jellyfish can reach lengths greater than 100 feet. Regardless of their size or shape, most jellyfish are very fragile, often containing less than 5% solid organic matter.

Jellyfish inhabit every major oceanic area of the world and are capable of withstanding a wide range of temperatures and salinities. Most live in shallow coastal waters, but a few inhabit depths of 12,000 feet!

Life Cycles

The life cycle of a typical jellyfish involves an alteration of generations in which the animal passes through two different body forms. The dominant and conspicuous medusa is the familiar form, while the smaller polyp form is restricted to the larval stage. Jellyfish are either male or female and reproduce sexually. The reproductive organs (gonads) develop in the lining of the gut. During reproduction, the male releases sperm through its mouth into the water column. The sperm swims into the mouth of the female where fertilizationoccurs. Early embryonic development begins either inside the female or in brood pouches along the oral arms. Small swimming larvae (planula) leave the mouth or brood pouches and enter the water column. The larvae then seek a shaded surface and attach to the bottom, forming polyps. These polyps divide and bud into young jellyfish (ephyra). In a few weeks, an ephyra will grow into an adult medusa, thus completing the complex life cycle. Jellyfish normally live three to six months.

Locomotion

The adult jellyfish drifts in the water with limited control over its movements. It is, however, endowed with muscles that allow it to contract its bell, reducing the space under it, forcing water out through the opening. This pulsating rhythm allows for some regulation of vertical movement. Because jellyfish are sensitive to light, this vertical movement can be important. Some jellyfish, like the sea wasp, descend to deeper waters during the bright sun of the midday and surface during early morning, late afternoon and evenings. Despite this ability to move vertically, jellyfish depend upon ocean currents, tides and wind for horizontal movement.

Food

Jellyfish may appear to have no apparent value, but they are, in fact, a very important part of the marine food web. Jellyfish are carnivorous, feeding mostly on a variety of zooplankton, comb jellies and occasionally other jellyfish. Larger species, however, are capable of capturing and devouring large crustaceans and other marine organisms. Jellyfish themselves are preyed upon by spadefish, sunfish, loggerhead turtles and other marine organisms. One species, the mushroom jelly, is even considered a delicacy by humans. Both fresh and pickled mushroom jellyfish are consumed in large quantities in China and Japan.



Venom Apparatus Jellyfish are equipped with a specialized venom apparatus (cnidoblast) for defense and feeding. A capsule (nematocyst) inside the cnidoblast contains a trigger and a stinging structure. The stinging structure varies according to species, but generally consists of a hollow coiled thread with barbs lining its surface. Nematocysts are concentrated on the tentacles or oral arms. A single tentacle can have hundreds or thousands of nematocysts embedded in the epidermis. Triggers of nematocysts are activated when contact is made with another object. Pressure within the nematocyst forces the stinging thread to rapidly uncoil. The thousands of nematocysts act as small harpoons, firing into prey, injecting paralyzing toxins. Stings usually paralyze or kill only small creatures but some jellyfish are harmful to humans. Jellyfish do not "attack" humans. Stings occur when swimmers or beachcombers come in contact with nematocysts. Severity of stings depends on the species of jellyfish, the penetrating power of the nematocyst, the thickness of exposed skin of the victim and the sensitivity of the victim to the venom. The majority of stings from jellyfish occur in tropical and warm temperate waters.

Cannonball Jelly (Stomolophus meleagris) Also know as jellyballs, these jellyfish are the most common in our area. During the summer and fall, large numbers of Stomolophus appear near the coast and in the months of estuaries. They are considered to be pests by commercial trawl fishermen because they clog and damage nets and slow sorting and trawl times. Fortunately, while the cannonball is the most abundant jellyfish in the area, it is also one of the least venomous. Cannonballs can be identified by their hemispherical white bells decorated with rich, chocolate brown bands. They have no tentacle but a gristle-like feeding apparatus formed by the joining of the oral arms. Cannonballs rarely grow larger than 8 inches in diameter.





Mushroom Jelly (Rhopilema verrilli) The mushroom jelly is often mistaken for the cannonball jelly, but it differs in many ways. The larger mushroom jelly, growing to 20 inches in diameter, lacks the brown bands associated with the cannonball and is much flatter and softer. Like the cannonball, the mushroom has no tentacles, however, it possesses long finger-like appendages hanging from the feeding apparatus. The mushroom jelly does not represent a hazard to humans.

Moon Jelly (Aurelia aurita) Probably the most widely recognized jellyfish, the moon jelly is relatively infrequent in South Carolina waters. It has a transparent, saucer-shaped bell and is easily identified by the four pink horseshoe-shaped gonads visible through the bell. It typically reaches 6-8 inches in diameter, but some are known to exceed 20 inches. The moon jelly is only slightly venomous. Contact can produce symptoms from immediate prickly sensations to mild burning. Pain is usually restricted to immediate area of contact.



Lion's Mane (Cyanea capillata) Also know as the winter jelly, the lion's mane typically appears during colder months of the year. The bell, measuring 6-8 inches, is saucer-shaped with reddish brown oral arms and eight clusters of tentacles hanging underneath. Cyanea are generally considered moderate stingers. Symptoms are similar to those of the moon jelly, however, usually more intense. Pain is relatively mild and often described as burning rather than stinging.



Sea Nettle (Chrysaora quinquecirrha) The sea nettle is frequently observed in South Carolina waters during summer months. This jellyfish is saucer- shaped with brown or red pigments, usually 6-8 inches in diameter. Four oral arms and long marginal tentacles hang from the bell. Considered moderate to severe, symptoms from sea nettle stings are similar to those of the lion's mane.

Sea Wasp (Chiropsalmus quadrumanus) Known as the box jelly because of its cube-shaped bell, the sea wasp is the most venomous jellyfish inhabiting our waters. Their potent sting can cause severe dermatitis and may even require hospitalization. Sea wasps are strong, graceful swimmers reaching 5-6 inches in diameter and 4-6 inches in height. Several long tentacles hang from the four corners of the cube. A similar species, the four-tentacledTamoya haplonema, also occurs in our waters.

Portuguese Man-of-War (Physalia physalis) Although a member of the phylum Cnidaria, the Portuguese man-of-war is not a "true" jellyfish. These animals consist of a complex colony of individual members, including a float, modified feeding polyps and reproductive medusae. Physalia typically inhabit the warm waters of the tropics, sub-tropics and Gulf Stream. , swimmers should learn to identify these highly venomous creatures. The gas-filled float of the man-of-war is purple-blue and can reach lengths of 12 inches. Under thefloat, tentacles equipped with thousands of nematocysts hang from the feeding polyps extending up to 65 feet.

The man-of-war can inflict extremely painful stings. Symptoms include severe shooting pain described as a shocklike sensation, and intense joint and muscle pain. Pain may be accompanied by headaches, shock, collapse, faintness, hysteria, chills, fever, nausea and vomiting. Initial contact with Physalia may result in only a small number of stings. However, efforts to escape from the tentacles may further discharge nematocysts and intensify stings. Care should be taken when removing the adhering tentacles. Severe stings can occur even when the animal is beached or dead.



Sea Anemones

sea anemones can travel three to four inches an hour. Sometimes sea anemones hitch a ride on hermit crabs or decorator crabs. If they do that, the sea anemone can protect the crab and if the crab is a messy eater, the sea anemone can pick up bits of food from the crab and eat it. Some sea anemones just let go of the rock and go float around in the water. The sea anemone eats small fish and shrimp. The sea anemone captures its prey with its deadly stinging tentacles. The sea anemone's mouth and tentacles are located on the top of its body. Sea anemones reproduce by budding off baby sea anemones. The babies stay connected to the adult until it is old enough to go out on their own. If a sea anemone is torn apart by rocks, then each part becomes a new sea anemone.

Diet fish, shrimp, isopods, amphipods and plankton Size 5 centimeters to 17 centimeters

Color all colors Life Cycle reproduce by budding

Predators nudibranchs, snails, fish and sea stars

Neat Facts pieces of sea anemones can turn into new sea anemones Types giant green, aggregated, brooding, painted, proliferating, rose, sand-rose, strawberry, tube, white spotted rose, white plumed, zoanthid

Relatives corals, hydroids, jellyfish, sea fans, sea pansies, sea pens



SEA CUCUMBERS



Hawaiian name: loli

Scientific name: Holothuroidea

Size: variable, 1 inch (2.5 cm) to 3 feet (0.9 m), depending upon species

Diet: detritus (plant and animal organic debris)



Sea cucumbers are "spiny animals", members of the grouping, or phylum, Echinodermata and relatives of the seastars and sea urchins. All echinoderms are marine and nearly all are bottom-dwellers. They are unique in having a 5-part body design and a water-vascular system of muscular internal canals which provides hydraulic power for their many muscular tube feet. Echinoderms lack a distinct "head" end, and most live mouth-side down on the seafloor. They have a large internal body cavity that is fluid-filled, and circulating fluids carry gases and nutrients throughout the body. Echinoderms have an internal skeleton of calcium carbonate plates called ossicles, and in familiar echinoderms the sea urchins, extensions of the skeleton form the spines for which this group is named.

Sea cucumbers differ from other echinoderms in having an elongate, cylindrical body with the mouth and anus at opposite ends. Because their body is muscular and soft rather than spiny, sea cucumbers are sometimes confused with sea slugs (snail relatives that lack a prominent shell). An easy way to tell sea hares and sea cucumbers apart is to look for a head. Sea slugs, like snails, have a head with sensory tentacles. Sea cucumbers, like other echinoderms, lack a distinct "head". Instead, the mouth end of a sea cucumber is ringed by 5 feeding tentacles used in gathering food particles. Sea cucumbers either gather detritus (bits of plant and animal matter) and bacteria from seafloor sediments or filter particles from the water.

Sea cucumbers lack some features common in other echinoderms. The 5-part body design you can see in seastars and even sea urchins is harder to find in many sea cucumbers. Some sea cucumbers have 5 rows of tube feet running the length of the body. But, in many sea cucumbers, you have to look internally to see the pattern -- five muscle bands run the length of the body. A few sea cucumbers have 5 "teeth" around the anal opening. These "rump teeth" are not used in feeding, but may protect the cucumber from parasitic fish that shelter in the cucumber's body.

The skeleton and spines that are so prominent in other echinoderms are reduced in sea cucumbers. Instead of a rigid skeleton, sea cucumbers have a muscular body well that contains only microscopic skeletal ossicles. The muscular body wall provides support, and so does the water inside the cucumber's large body cavity. This "water skeleton" also acts like a circulatory system.

Like other echinoderms, nearly all sea cucumbers have tube feet. The suckered tube feet are important for both attachment and movement. In many species, the tube feet are all found on one side of the animal, providing greater grip in wave-swept habitats. One group of sea cucumbers (synapid or apodous cucumbers) lack tube feet all together and move by muscular waves which pass down the length of the body (peristalsis) – they are found in quiet-water habitats.

Sea cucumbers have some structures that other echinoderms don't! A special respiratory structure, called the respiratory tree, is derived from a branch of the sea cucumber lower digestive tract. So, cucumbers obtain oxygen by pumping seawater in and out of the anus. The water that may drain from a sea cucumber's body is "exhaled" water from the respiratory tree.

Sea cucumbers may lack spines and the protection of a rigid skeleton, but they have many different means of defense from predators. With soft, flexible bodies, they are able to crawl under rocks and into reef crevices. Some species have repellant or toxic chemicals in the skin that make them distasteful. Others eject sticky threads (Cuvierian tubules) from the anus -- these threads entangle and immobilize potential predators and the cucumber crawls to safety. Still other sea cucumbers can eject (evicerate) part of the digestive system as a defensive mechanism, regenerating lost parts later.

Like most echinoderms, sea cucumbers reproduce sexually and many are broadcast spawners. Males release sperm and females release eggs into the water and fertilization is external. A barrel-shaped planktonic larva results that drifts in plankton before settling to the seafloor and metamorphizing into a benthic (bottom-dwelling form). A few sea cucumber species retain the young and brood them until they emerge as crawling juveniles. Some species have also been reported to reproduce by fission (splitting in half), a form asexual reproduction

There are more than fourteen species of sea cucumbers in Hawaii's shallow waters, ranging in size from about 1 inch (2.5 cm) to 3 feet (0.9 m). They occur in tide pools, on reefs, in bays and lagoons, and in deeper waters. Examples of common tidepool species are the black sea cucumber (Holothuria atra), ashy cucumber (Holothuria cinerasens), banded sea cucumber (Holothuria pervicax), and white-speckled (rump-toothed) sea cucumber (Actinopyga mauritiana). In the quiet waters of Käne‘ohe Bay, the prickly sea cucumber (Ophiodesoma spectabilis) is common. Sea cucumbers, in general, were known as loli by early Hawaiians, but only certain species were eaten. Sea cucumbers are highly prized as a delicacy in many cultures including those of Asia, Pacific Islands, and Mediterranean Europe.

Sea cucumbers play an important role in reef "recycling". They feed by gathering organic detritus and even bacteria from the water or the sand. They speed the breakdown of these bits of plant and animal debris -- extracting energy for their own survival and recycling materials that seaweeds can absorb as fertilizers. The sand that sea cucumbers process along with the detritus they consume is eliminated as strings of sandy beads. This processing helps "turn over" sediments.

Classification:

Kingdom Animalia

Phylum Echinodermata

Class Holothuroidea



Sea Pens

One of the most distinctive groups of "soft corals," or octocorals, is the Pennatulacea, or "sea pens." As is the case for all octocorals, sea pens are actually colonies of polyps. What distinguishes sea pens is polyp dimorphism. One polyp grows very large and loses its tentacles, forming the central axis. The base of this primary polyp forms a bulb which may be expanded or contracted; the sea pen uses this bulb to anchor itself. Branching off this primary polyp are various secondary polyps. Some, called autozooids, are typical feeding polyps. Others, the larger and fewer siphonozooids, serve as intakes for water, which circulates within the colony and helps keep it upright. Also supporting the colony are calcareous spicules and frequently a central axial rod of calcium carbonate.

In one group of sea pens, called the Subselliflorae, the secondary polyps are grouped into "polyp leaves," as in the Pacific species of Sarcoptilon shown here. The feather-like appearance of these species gives the sea pens their common name; they look something like old-fashioned quill pens. Most species, however, do not have polyp leaves, and look more like clubs, umbrellas, or pinwheels. The unusual "sea pansy," Renilla has a primary polyp that is broad and flattened, with autozooids and siphonozooids on the upper surface. Renilla is actually able to crawl about on its leaflike primary polyp.

Sea Fans

The Subclass Alcyonaria contains the so-called "soft corals" , which include such forms as sea fans, sea whips, sea pens, sea pansies, etc. Sometimes they are also called the octocorals because they have octomerous symmetry, with eight pinnate tentacles and eight complete septa. All forms are colonial, and the polyps of the communicate through a series of gastrodermal tubes called solenia that run through an extensive network in the mesoglea. The endoskeleton, which is secreted within the mesoglea and consists of calcium carbonate spicules, fused spicules and horny protein, provides support for many colorful forms such as sea fans, gorgonians, sea pens, sea whips, etc. that form "submarine gardens" in tropical waters.

The Hydroid Hydroids fool many people by looking like feathery plants or fireweed. The truth of the matter is that Hydroids are colonies of animals with strong stinging cells used to capture prey and to fight of predators. Some of the species can cause great pain with the stinging of these stinging cells. Divers take great caution about brushing against these hydroids. The two dangerous types of hydroids are white, fine feathery and the denser brown/yellow type. These hydroids may be found in fairly shallow coral reef areas and on wharfs.

"Sea Pansy"

Renilla reniformis "Sea Pansy" The Sea Pansy is quite frequently found washed ashore on northeast Florida beaches following northeasterly winds
rough surf conditions. It also can often be found living intertidally (in-situ) completely buried in the sand. The Sea Pansy is an anthozoan and is a collection of polyps having different forms and functions. A single, giant polyp up to two inches in diameter forms the anchoring stem (peduncle). This peduncle can be distended to better anchor the colony in the substrate. The sea pansy is strikingly bioluminescent when disturbed, due to Green Fluorescent Protein, a molecule that has become extremely important recently for modern biological science.

Taken from various sources in a set of Natural Science books published by Random house in 1968

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