Characteristics of Simple Worms

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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.

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• 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).

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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

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• 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

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• 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

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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. Tubeworms have flower-like antennae.
• 2. Bristleworms sting when touched.
• 3. Spongeworms live on sponges.
• 4. Fireworms live on the surface of fire coral.

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Other types

1. Oligochaetes class Hirudinea. They are
   earthworm relatives
2. Leeches most are freshwater, those that are
   marine water typically live on another fish.
   They have no parapodia
3. Sipunculans unsegmented bodies and bury
   themselves in mud. Exclusively marine and in
   shallow waters

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1. Echiurans over 100 species and are exclusively
   marine
2. Pogonophora lack a digestive system (including
   mouth and gut). Also known as beard worms
3. Chaetognaths one of the smallest animal phyla.
   They have eyes, teeth, grasping spines,
   transparent and fish like fins and tails

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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

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• 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

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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

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• 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

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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

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• 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.

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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

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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

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Mussels

• Do not burrow
• Instead attaches to rocks and other surfaces
  using byssal threads

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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

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• 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

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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

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• 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

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• 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.

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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

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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

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• 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

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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

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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

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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

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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

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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.

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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.

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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

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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.

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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.

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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

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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

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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

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Characteristics of Echinoderms

• Even though the organisms in phylum Echinodermata
  dont 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.

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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.

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Special Attributes of Sea Stars

• Sea stars belong to class Asteroidea.
• They are predators with downward-facing mouths.
• They have tube feet covering their undersides.
• They usually have five arms.
• A few species have toxic spines for protection.
• Each arm carries an equal share of theanimals
  systems and organs.
• They can regenerate a lost limb, some growinto
  several new animals when cut into pieces.

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Special Attributes of Brittle Stars

• Brittle stars belong to class Ophiuroidea.
• This class has slender legs that are
  proportionatelylonger and thinner than those on
  sea stars.
• Brittle stars feed on detritus and small animals.
• They use arms and tube feet for locomotion.

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Special Attributes of Sand Dollars and Sea Urchins

• Sand dollars and sea urchins are part of class
  Echinoidea.
• They have the five-section body, but no arms.
• Sand dollars and sea urchins share a disk-shaped
  body.
• They have tube feet on the underside.
• Sea urchins graze on algae.
• Swimmers avoid sea urchins because of their
  spines.
• Some species have toxins in the spines for
  self-defense.
• Urchins can move their spines to assist in
  locomotion.

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Special Attributes of Sea Cucumbers

• Sea cucumbers are part of class Holothuroidea.
• They have an elongated five-segment body with
  tentacles around the mouth.
• Most feed by moving with their mouths open,
  allowing sandto flow through. A few are filter
  feeders.
• Some expel a sticky mass of white tubes covered
  in toxin.
• They are protected by tough skins and by the
  ability to expelpart of their internal organs
  for predators while saving the rest to survive.

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Digestion

• Carnivorous
• They invert stomach through the mouth to envelope
  food
• The intestine is short or missing
• The body cavity is filled with a coelomic fluid
• Also serves to bring in oxygen.
• Sea cucumbers bring in water through the anus to
  the respiratory branches
• Extensions of gut

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Reproduction

• They have separate sexes with 5, 10, or more
  gonads that shed sperm or eggs
• Spawning
• Gametes do not survive long in the water
• Individual spawn all at once
• Fertilized egg develop into the plankton and
  results in a ciliated larva
• Some echinoderms carry eggs

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• Asexual reproduction
• Fission
• The central disk splits into 2 new individuals
• Regeneration
• The ability to grow missing parts
• Requires that part of the central disk be present
  to grow a new individual
• Sea star do not require the disk