Reef corals may form 1 fringing reefs extending out to 0. A wide variety of marine invertebrates, including sponges, jellyfish, sea anemones, corals, gastropods and turbellarians harbor within them golden spherical cells termed zooxanthellae. The photosynthetic activity of these symbiotic algal cells is vital to the survival of the individual coral animals and to the entire reef ecosystem.
The zooxanthellae include several species of unicellular algae in the order Zooxanthellales within the algal division Pyrrophyta also spelled Pyrrhophyta. The term zoochlorellae refer to several species of symbiotic unicellular green algae of the division Chlorophyta. Along the Pacific coast of North America, zoochlorellae produce the greenish color in sea anemone tentacles. A pristine tide pool along the Oregon coast of North America.
Purple sea urchin, B. Blood Starfish, C. Coralline red algae, D. Six-rayed starfish, and E. Sea anemone. The tentacles of the sea anemone contain zoochlorellae, symbiotic green cells of the algal division Chlorophyta. A sea anemone and its symbiotic anemone fish. Three comb jellies ctenophores. Comb jellies resemble tiny hot air ballons the size of a walnut or smaller with eight rows of fused cilia comb plates extending down the sides.
They propel themselves mouth first by the eight rows of comb plates. Ctenophores superficially resemble miniature medusae phylum Cnidaria ; however, most medusae arise asexually from a polyp generation and ctenophores have no polyp stage in their life cycle. Tentacles extending from the mouth contain "glue cells" or colloblasts containing spiral threads which snare small fish and crustaceans with a gluelike material.
With the exception of one species, ctenophores do not have the stinging organelles nematocysts of jellyfish and sea anemones. During the day, ctenophores flash prismatically as their ciliary plates refract light; at night they are often bioluminescent, glowing like little lamps. Is this a 1 wet pajama draw string, 2 a long noodle, or 3 a human tapeworm? The answer is 3 , a 20 inch 50 cm human tapeworm. The small head or scolex from which the segments progottids arise is clearly visible in the photograph.
The presence of a scolex is good evidence that the entire worm has been discharged from the host's intestine. Each proglottid contains a complete male and female reproductive system. In fact, one proglottid may contain literally thousands of eggs. Magnified view 30X of the human tapeworm shown in the above photograph showing the anterior end or scolex.
The scolex bears four circular suckers which firmly anchor the tapeworm to the host's intestinal wall. The scolex produces proglottids by budding, which gradually enlarge as more segments are formed. Tardigrades belong to a remarkable phylum of minute multicellular animals. They are adapted to extreme conditions, some of which are more severe than any earth environment. Does their origin defy natural selection?
Lateral side view of the exoskeleton of an aquatic tardigrade Hypsibius sp. There are 4 pairs of stout, stumpy legs, each tipped with several slender claws. The name "water bear" refers to its deliberate "pawing" sort of locomotion.
Thomas Huxley, English naturalist and good friend of Charles Darwin, gave tardigrades this name in Photographed with a Sony W digital camera through an Olympus laboratory grade compound microscope x magnification.
An aquatic tardigrade of the genus Hypsibius. Its length is approximately micrometers microns , about the same length as the hair follicle mite Demodex brevis.
It is much smaller than a grain of common table salt NaCl. The image was enhanced with Photoshop to bring out detail of the claws.
Magnification x. M4V file. Mesozoic rock from Arizona showing numerous brachiopods, evidence of a shallow sea along a continental shelf. An articulate hinged brachiopod. Gastropods shells cowries and cone shells from the south Pacific island of Moorea and Tetiaroa Atoll in French Polynesia. The lower right shell is from a land snail. The common garden snail Helix aspersa. Arthropods have segmented bodies. Each body segment usually has a pair of appendages. The appendages can be antennae, wings, legs, or mouthparts!
The protostome coelomates acoelomates and pseudocoelomates are also protostomes include the mollusks, annelids , arthropods, pogonophorans, apometamerans, tardigrades, onychophorans, phoronids, brachiopods, and bryozoans.
Deuterostomes include the chaetognaths, echinoderms, hemichordates, and chordates. Respiratory system Aquatic arthropods crustaceans and the chelicerate horseshoe crabs possess gills for respiration. Terrestrial arthropods possess tracheae and book lungs as respiratory organs. Tracheae are a system of tiny tubes that permit passage of gases into the interior of the body. Arthropods also have a hemocoel, an open body cavity in which blood flows and bathes the tissues and organs.
The dorsal tubular heart is perforated by pores ostia ; arthropods generally lack blood vessels. Like all animals, arthropods need oxygen to survive. Some small arthropods simply absorb oxygen through their thin body coverings. Larger aquatic species breathe through feathery, fishlike gills. Insects and some other land arthropods breathe through a system of tiny body tubes called tracheae. In addition to having a body cavity, organisms with pseudocoeloms also have a complete digestive tract -- separate openings for food to enter and undigested material to leave.
This makes digestion and feeding more efficient because the animal can eat before it has finished digesting its previous meal. Do arthropods have Coelom? Category: pets fish and aquariums. Similar to annelids, arthropods are coelomates with a true coelom , or body cavity.
Centipedes are very dangerous, and their bite is extremely painful. Class Diplopoda - 10, sp. Millipedes share the same habitat as centipedes, but they are mostly herbivorous, feeding on decaying vegetation in the leaf litter. Animals that feed on detritus are called detritivores. Each segment of the millipede is actually two segments fused together hence the double set of legs.
They can secrete a defensive fluid that smells bad, and a few species actually secrete tiny amounts of cyanide gas to protect themselves! Class Insecta - , sp.
If we knew all the different insects on Earth, there could be as many as 30 million species. Insects evolved about mya, with cockroaches and dragonflies among the first to appear. Insects have a head, thorax, and abdomen, with three pair of legs 6 legs on the thorax. Crustaceans have legs on the abdomen as well as on the thorax. Most insects have one or two pairs of wings. They are the only invertebrates that fly.
Most have compound eyes , and can communicate by sound and scent, using powerful chemical hormones called pheromones. Insects have extremely elaborate mouthparts, consisting of pairs of appendages fused into a lower lip labium , and an upper lip labrum , with other appendages called maxillae aiding in chewing.
These mouthparts are highly modified in various groups for chewing, sucking, and piercing. Insects undergo metamorphosis as they develop, changing from one form to another as they mature.
The juvenile stages look like tiny versions of the adults. Their larvae are often radically different from the mature adult like the butterfly and the caterpillar. They not only look different, they live in different places and eat different food. Observe the preserved arthropods on display. How do the various groups use their legs to walk, swim, feed or mate? Watch the way the millipede moves.
Look at the legs. See how the waves of muscle contraction pass down through the segments? The polychaete worm Nereis moves in exactly the same way. Handle the millipedes very gently. They are someone's pets. They also make great pets for dorm rooms - they need little care, don't take up much room, and don't make noise or messes, unlike your roommate. Disturb the centipedes to get them moving around. Can you see the poison fangs? Notice how flat the body is, and contrast the number of legs with those of the millipede.
Why does each container hold only a single centipede? Don't open the jars unless you have a thing for extreme pain. Play around with the roly-polys. Oh, go ahead, it's cool. They won't bite. Watch the way they roll up into a ball when disturbed. Not all isopods can do this, but rolling up into an armored ball is a great defensive tactic. Compare our teeny tiny terrestrial version with the enormous preserved marine isopods. Look at the live brine shrimp, hermit crabs and fiddler crabs.
Treat them gently more pets. Watch the way they use their legs, including the modified legs that form their mouthparts. You may see the male fiddler crabs raise their large claw and wave it about to claim a territory inside the tank, in the hopes of attracting a mate Can you blame them?
Observe the live crayfish. What does the crayfish do when it feels threatened? How does it use its swimmerets when it is stationary? Pearse, M. Buchsbaum, and R. Living Invertebrates. To cite this page: Myers, P. Disclaimer: The Animal Diversity Web is an educational resource written largely by and for college students. ADW doesn't cover all species in the world, nor does it include all the latest scientific information about organisms we describe.
Though we edit our accounts for accuracy, we cannot guarantee all information in those accounts. While ADW staff and contributors provide references to books and websites that we believe are reputable, we cannot necessarily endorse the contents of references beyond our control. Arthropoda arthropods Facebook. Sources : Hickman, C. Animal Diversity.
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