Characteristics of Simple Worms Phylum Platyhelminthes is made up of flat worms. They have a flattened tube of muscle, simple digestive system,a single opening that serves as both mouth and anus. Phylum Nemertea are more complex with a flat shape. They have a simple blood vascular system, one-way digestivesystem, separate mouth, and anus. They are carnivores.
Phylum Nematoda are structurally simple round worms. • More complex than the other two phyla. Most are parasiticworms, some live in sea animals. • This phylum also includes human parasite forms. Special Attributes of Simple Worms • Lineus longissimus, a nemertean, found in theNorth Sea is perhaps the longest known creature in theworld – more than 60 meters (197 feet).
Features of segmented worms • Members of the Phylum Annelida (which means little rings) • Most are in the class Polychata • 6000 species of polychata • Tube-shaped body divided into segments (which is where the name comes from) • Found: • Fresh water • Salt water • Moist soil
They have a body cavity which holds their organs • Closed circulatory system • Crawling worms (2- 4 inches) are carnivores • Those that burrow are deposit feeders • They all have “Setae” • Bristle-like structures on the sides of each segment • Helps worms move through the soil and hold on to the soil • Some have developed gills on these
The planktonic larval phase is called a trochophore • Band of cilia around the body • Some species can reproduce asexually by fission. Earthworms do NOT reproduce asexually. They reproduce sexually. They are hermaphroditic. Other annelids are either male or female. • Most live in tubes made of mucus, seaweed, cemented mud, etc
Characteristics of Annelids Worms in phylum Annelida stand apartbecause of their structural complexity. They have a heart, nephridia, and sometimes, jaws. Most important, they exhibit metamerism– the division of the body into repeating blocks or segments. Special Attributes of Annelids Of particular relevance to oceanography – class Polychaeta, because many polychaete worms live in the marine environment. 1. Tubewormshave flower-like “antennae.” 2. Bristlewormssting when touched. 3. Spongewormslive on sponges. 4. Firewormslive on the surface of fire coral.
Other types • Oligochaetes = class Hirudinea. They are earthworm relatives • Leeches = most are freshwater, those that are marine water typically live on another fish. They have no parapodia • Sipunculans = unsegmented bodies and bury themselves in mud. Exclusively marine and in shallow waters
Echiurans = over 100 species and are exclusively marine • Pogonophora = lack a digestive system (including mouth and gut). Also known as beard worms • Chaetognaths = one of the smallest animal phyla. They have eyes, teeth, grasping spines, transparent and fish like fins and tails
Characteristics of Mollusks Phylum Mollusca – the mollusks – ranges from squid and octopuses to sea slugs, snails, oysters, clams, and conches. It has the most species of any other ocean group Making it the most successful at 110,00 species Immense diversity in structure and habitat Can be found in splash zones of rocky shores to deep sea hydrothermal vents Can thrive on just about every concievable diet
Three characteristics all members share: • A muscular bag called the mantle. • A thin layer of tissue that covers the body • Produces the shell • Shell is made of CaCO3 to protect its soft body • A muscular foot beneath the head (ventral). • Used for locomotion • Most have a head with eyes, sensory organs, and a radula (a tongue with rough scraping teeth used for feeding). • Radula is made of Chitin • A highly resistant material found in many invertebrate • Bodies are unsegmented, Bilaterally symmetrical bodies
All mullusks have the same basic body plan with some modifications • Shell is internal in squids and absent in sea slugs and octopuses • Portions of the body are coiled and asymmetrical in snails • The radula is modified or absent in some mollusks
Special Attributes of Class Gastropoda • Snails, whelks, slugs, and most single-shelled mollusks belong in class Gastropoda. • 75,000 species, mostly marine • Basically a coiled mass of vital organs enclosed by a dorsal shell • Shell is usually coiled and rests of the on a ventral creeping foot
Varied types of feeding • Use radula to scrape algae from rocks • Periwinkles, limpets, abalone • Deposit feeders feed off of soft bottoms • Mud snail • Carnivores • Whelks, oyster drills, cone shells • They specialize in prey like clams, oysters, worms, and even small fish • Violet snails prey on siphonophores • Sea slugs (nudi-branch) feed off of sponges and hydroids • They use noxious chemicals and nematocysts
Torsion is a developmental process. • It occurs after the veliger settles and begins maturing. Its body twists into a permanent loop that rearranges the organs and brings them together allowing the body to draw into the spiral shell common to this class.
Class Bivalvia Belonging to class Bivalvia (bi meaning two) are mollusks that have two hinged shells. Mussels, clams, oysters, and scallops are all bivalves. Has the basic Mollusk structure Body is laterally compressed and enclosed in 2 valved shells No head nor radula Gills used for breathing Oxygen and sorting small food particles Inner surface lined by a mantle body lies in mantle cavity
Clams • Use a shovel-shaped foot to burrow in sand and mud • Forms siphons by fusing edge of mantle to draw in and out water to allow clams to feed and obtain oxygen while buried in sediment
Mussels • Do not burrow • Instead attaches to rocks and other surfaces using byssal threads
Oysters • Cement shell to hard surfaces • Often another oyster • Pearls form when oysters secretes CaCO3 to coat an irritant • Can be particles of sand to parasites lodged between the mantle and the iridescent • Cultured pearls are obtained by carefully inserting bits of shell or plastice
Some scallops live unattached and swim for short distance by rapidly ejecting water from mantle cavity and clapping valves • Giant clam is the largest bivalve at over 1 meter long • Fouling organism is a common problem for ocean cities • Some bivalves attach to wood such as on boats
Class Cephalopoda • They are all predators that specialize in locomotion • Very agile swimmers, displaying a complex nervous system • They have a reduced or eliminated shell • The basic structure is a head pushed down toward a foot that has been modified as arms equipped with suckers to capture prey
They have eyes that are similar to ours in structure • Bodies are protected by a thick muscular mantle • Elongated in squid, rounded in octopuses • Mantle forms a mantle cavity enclosing 2 or 4 gills • They have a structure called a “Funnel” • Muscular tube formed by what remains of the foot used as siphon (an exit for water that enters through a free edge of the mantle • Used for swimming by forcing water out • Funnel is flexible allowing it to be relocated
This class includes cuttlefish, squid and octopuses. • Cuttlefish (order Sepioidea) differ from squid and octopuses by having an internal shell used primarily for buoyancy. • Squid (order Teuthoidea) differ from cuttlefish and octopuses with their streamlined, torpedo-shaped bodies adapted to life in open water. • Octopuses (order Octopoda) differ from squid and cuttlefish by having no shell and living in rocky reefs and coral. • Octopuses are probably the most intelligent invertebrates.
Biology of Mollusks Digestion • Contain a separate anus and mouth • Digestion involves digestive glands such as salivary glands that release enzymes which break down food into simpler molecules • Circulatory system transports nutrients and oxygen to cells using a dorsal, muscular heart • Most mollusk have an open circulatory system • All cephalopods have a closed system
Differences in digestion • Chitons and snails use a combination of extracellular and intracellular digestion • Snails keep chloroplast intact and continue to carry put photosynthesis • Carnivorous snails modify radula to drill and capture prey. May even have jaws. • All extracellular • Bivalves have long strings of mucus in mouth to trap food
Crystalline style in stomach rotates food to help digest • Contents eventually pass into large digestive gland for intracellular digestion • Giant clams contain zooxanthellae that live in tiny branches of gut that extend into mantle for extra nutrients • Cephalopods are entirely extracellular. Stomach is connected to an extra sac to speed up digestion
Nervous System and Behavior • Snails, chiton, and bivalves possess a ganglia • Cephalopods have a true brain. • Design of their brain is similar to humans • Like humans, body is controlled through a combination of nerve fibers and the brain • High learning capacity • Can control color change depending on mood
Reproduction and Life History • Some are hermaphrodites • Bivalves, chitons, and some snails fertilize externally • Cephalopods and most snails are internal • Males modify an arm to transfer a spermatophore • Snails use a long, flexible penis • Female octopuses protect the eggs until hatched • Young develop in yolk-filled egg • Female usually dies after eggs hatch
Arthropods Phylum Arthropoda is the most numerous of multicellular animal phyla. There are several intermediate classifications. There may be as many as one million arthropod species. 3 out every 4 animals is an arthropod Characteristics: segmented bodies, jointed legs, a chitinous exoskeleton. Segmented bodies with bilateral symmetry Segmentation adds flexibility Jointed appendages Including the mouth Moved by sets of attached muscles They have a chitinous exoskeleton Secreted by underlying layer of tissue Tough, non-living material
Growth • In order to grow, arthropods must shed their rigid shells • Process is known as molting • Animal takes in water to expand and forms a new exoskeleton • Exoskeleton limits size and growth • Will never be a giant but exoskeleton and joints gives a successful combination of protection, support, flexibility, and increase surface area for muscle attachments
Superclass Crustacea – an intermediate classification. • Characteristics include: • A pair of appendages on each body segment. • Specialized for swimming • Two pairs of antennae. • Mandibles for chewing. • Teardrop-shaped larvae. • Exoskeletons are shed as they grow.
Special Attributes Krill Class Malacostraca includes two orders of interest due to their roles as food for humans and food for nature. Order Euphausiacea: krill Krill are important primary and secondary consumers that link smaller plankton to larger consumers. In subpolar food webs, they are vital. Whales, seals, sea birds, and penguins only survive in highly productive waters. Much of the food web above krill depends on it for life.
Decapods • 10 legs • 1st pair usually has claws to obtain food and defend • Referred to as cheliped • Rest of body is divided into the Cephalothorax and abdomen • Have claws and an extended carapace that encloses the gills. • Because humans eat these shellfish, they are an important food source and resource on which the fishing industry relies. • Includes shrimp, lobster, crabs, hermit crabs • Hermit crabs are not actual crabs • Shrimps have laterally compressed bodies and elongated abdomen like a lobster • Also scavengers • Crabs have a broad cephalothorax and a tucked in abdomen
Special Attributes of Class Cirripedia Barnacles unique lifestyle sets them apart into class Cirripedia. Life begins as free-swimming larvae like other crustaceans. When the larva finds a surface on which to live (rocks, boats,etc.) it fuses itself in place “upside down.” The exoskeleton forms the carapace (hard shell) the barnaclecan withdraw into for protection.
Special Attributes of Copepods • Copepods play a central role in the ocean food webs. • They are important primary and secondary consumers ofphytoplankton and zooplankton. • Relatively few larger animals can consume the tiniest plankton, but many can eat the larger copepods. Fish, krill, and giant planktonfeeders, including whale sharks, baleen whales, and manta rays all eat copepods. • Copepods are important to ocean food webs because they link the tiny primary producers and consumers to the large animals higher up the web.
Digestion • Filter feeder • Stiff, hair like fibers to catch food • Particles carried by currents caused by other moving appendages • Parasitic crustaceans have bristles used for piercing and sucking • Maxillipeds are the appendages closest to the mouth are turned upward and specialized to sort out food and push it in to the mouth • 3 pairs • Stomach has chitinous teeth/ridges for grinding and bristles for sifting
Nervous system and Behaviour • Small, simple brains that are more centralized in decapods • Highly developed sensory organs • They have compound eyes • In decapods eyes act as periscope • Keen sense of smell • Use a pair of statocysts for balance • Use signals to communicate with each other
Reproduction • Generally have 2 genders • Gametes are rarely shed into water • Males have a specialized appendages to transfer sperm • Even hermaphroditic species • Usually occurs immediately after female decapods molts • Can store sperm for long periods of time • Nauplius is a common crustacean larva
Characteristics of Echinoderms Even though the organisms in phylum Echinodermata don’t at first look and act much like animals, they are. They move. They attack prey. They defend themselves.They just tend to do so very slowly. They all share: A radially symmetrical body divided into five parts. Most have hundreds of tiny tube feet to crawl and climb. Most have a water vascular system thatbrings oxygen to the body cells. Echinoderms have some traits closeto chordates. The adult is radially symmetrical. The larvae are bilaterally symmetrical. Bilateral symmetry, along a vertical axis,is what mammals, fish, etc. have.
Special Attributes of Crinoids Class Crinoidea include feather stars and sea lilies. The primary characteristics of this class are: Long feather-like arms and short, hook-like legs called cirri. They have upward-facing mouths. Most are nocturnal feeders. At night, they unfurltheir arms to capture plankton and nutrients carriedinto their paths by the current. By day they coil up tightly and hide in the reef. Most crinoids attach to the bottom by their cirri.