Phylum Porifera- Sponges

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Phylum Porifera- Sponges

• Porifera means pore-bearer
• Sponges are
• Asymmetrical
• Sessile
• Contain cells only no tissues
• Choanocytes (collar cells) are flagellated
  cells that line the internal cavity of a sponge
  and aide in filtering food from the water

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Porifera continued

• As water leaves the sponge, waste products are
  washed away
• Some sponges have skeletons made of spicules
• Asexual (budding or fragmentation) and sexual
  reproduction (hermaphrodites)

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Phylum Cnidaria- Cnidarians

• No brain or central nervous system have a nerve
  net instead that aid in muscle contraction
• Radial symmetry
• Two tissue layers
• Endoderm (inner)
• Ectoderm (outer)
• Sexual (external fertilization) or asexual
  reproduction (budding)

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• Two basic body forms
• Medusa (free floating umbrella shape)
• Polyp (tube-like, usually attached to a
  substrate)
• Tentacles surround the opening of the
  gastrovascular cavity
• Each tentacle contain stinging cells called
  cnidocytes
• Within each cnidocyte is a small, barbed harpoon
  called a nematocyst
• Used for defense and to spear prey
• Some contain toxins that kill or merely stun
• The tentacles bring the prey into the
  gastrovascular cavity

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3 Types of Cnidarians

• Hydrozoaex. Hydra
• Include polyp and medusa stages
• Attached to substrates by an area on their body
  called a basal disk
• Scyphozoatrue jellyfish
• Active predators
• Mostly medusa stage but also have a polyp stage
• Anthozoaexist only as polyps
• Sea anemones and corals
• Most have a symbiotic relationship with protists

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Phylum Platyhelminthes Flat Worms

• Bilateral symmetry
• 3 tissue layers
• Mesoderm is middle tissue layer that helps form
  true organs
• Gastrovascular cavity

• Defined head and tail region
• Centralized nervous system containing a brain and
  nerve cords
• Eyespots for light detection

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More on Flatworms

• Flatworms are hermaphroditic and capable of
  sexual and asexual reproduction
• Passive diffusion through the skin supplies
  oxygen to their body parts
• Most species of flatworms are parasitic

Planaria
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Tapeworms and You!

• Generally infect vertebrates or humans
• Suckers and hook-like structures allow the
  tapeworm to permanently attach themselves to the
  inner wall of their hosts intestines
• Food is directly absorbed from the hosts
  intestines to the tapeworms skin
• Grow by producing a string of rectangular body
  sections called proglottids behind their head
• May grow up to 40 ft long!

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• Largest flatworm class consisting of parasitic
  worms called flukes
• Most have complex life cycles
• Some live inside their hosts making them
  endoparasites or outside their host making them
  ectoparasites
• Flukes do not have a well-developed digestive
  system because of its dependence on a host

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Phylum Nematoda Round worms

• 3 tissue layers
• Gases are exchanged through the fluid by
  diffusion
• Simplest animals to have a one-way digestive
  system
• Have long muscles that extend the length of the
  worm
• Allows the nematode to move whip-like
• Many cause human and plant diseases

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Roundworms and your pet!
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Roundworms Guinea Worms A Worldwide Problem

• What is dracunculiasis?
• Dracunculiasis, more commonly known as Guinea
  worm disease (GWD), is a preventable infection
  caused by the parasite Dracunculus medinensis.
  Infection affects poor communities in remote
  parts of Africa that do not have safe water to
  drink.
• How does Guinea worm disease spread?
• Adult female Dracunculus worms emerge from the
  skin of Infected persons annually. Persons with
  worms protruding through the skin may enter
  sources of drinking water and allow the worm to
  release larvae into the water. These larvae are
  eaten by fresh water water fleas where these
  develop into the infective stage in 10-14 days.
  Persons become infected by drinking water
  containing the water fleas that have the
  infective stage larvae of Dracunculus medinensis.

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Roundworms Pinworms and You!

• What are the symptoms of a pinworm infection?
• Itching around the anus, disturbed sleep, and
  irritability are common symptoms. If the
  infection is heavy, symptoms may also include
  loss of appetite, restlessness, and difficulty
  sleeping. Symptoms are caused by the female
  pinworm laying her eggs. Most symptoms of pinworm
  infection are mild many infected people have no
  symptoms.
• Who is at risk for pinworm infection?
• Pinworm is the most common worm infection in the
  United States. School-age children, followed by
  preschoolers, have the highest rates of
  infection. In some groups nearly 50 of children
  are infected. Infection often occurs in more than
  one family member. Adults are less likely to have
  pinworm infection, except mothers of infected
  children. Child care centers, and other
  institutional settings often have cases of
  pinworm infection.
• Danger of Sandboxes!

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Roundworms Elephantiasis

• What is lymphatic filariasis?
• Lymphatic filariasis is a parasitic disease
  caused by microscopic, thread-like worms. The
  adult worms only live in the human lymph system.
  The lymph system maintains the body's fluid
  balance and fights infections.
• How is lymphatic filariasis spread?
• The disease spreads from person to person by
  mosquito bites. When a mosquito bites a person
  who has lymphatic filariasis, microscopic worms
  circulating in the person's blood enter and
  infect the mosquito. People get lymphatic
  filariasis from the bite of an infected mosquito.

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Phylum Annelida Segmented worms

• Easily recognized by their segments which are in
  ring-like structures
• Each segment contains digestive, excretory,
  circulatory, and locomotor organs
• Simple brain located in head region
• Digestive tract

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• Have circular and longitudinal muscles which
  allow the worm to crawl
• Circular muscles contract to elongate the segment
• Longitudinal muscles contract to bunch up the
  segments
• Respiration occurs through the worms skin
• The digestive tract is divided into different
  regions for different functions of digestion
• Have external bristles called setae
• Located on each segment to increase traction
• Earthworms are hermaphrodites

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• Examples include polycheates, leeches and
  earthworms
• Earthworms eat detritus using this pathway
• Muscular pharynx, esophagus, crop, gizzard,
  intestine, anus
• Leeches have suckers at both ends of their body

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Phylum Mollusca Soft-bodied

• FYI Second largest animal phyla
• Examples snails, slugs, oysters, clams,
  scallops, octopuses, and squid
• Aquatic mollusks have gills for respiration,
  terrestrial mollusks have thin membranes that act
  as a primitive lung or do respiration through
  their skin
• Sexual reproduction

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Key characteristics shared by all mollusks

• All have
• Bilateral symmetry
• Digestive Tract
• Three-part body plan
• Visceral massa central section that contains the
  mollusks organs
• Mantlea heavy fold of tissue that wraps the
  visceral mass like a cape
• Secretes a shell in some mollusks
• Footmuscular region which is used primarily for
  movement or grasping
• Many have a radulaa rasping tongue-like organ
  located in their mouth

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• Gastropods Ex. Snails, slugs, nudibranchs
• Foot is adapted for locomotion
• Have various feeding habits mainly using their
  radulas
• Bivalves Ex. Clams, oysters, mussels
• Most are sessile but some like scallops will flap
  its valves to move
• Most bivalves are filter feeders

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Cephalopods (squids, nautiluses, octopuses)

• Large head attached to tentacles (foot divided
  into parts)
• Squid (10 tentacles), octopus (8 tentacles),
  nautilus (80-90 tentacles)
• Nautilus only living cephalopod with a shell
• Most intelligent of all invertebrates
• Have eyes similar to vertebrates eyes
• Have the largest eyes known in any animal
• Move by closing their mantle cavity to shoot
  water out forcefully
• All cephalopods are active marine predators
  feeding on fish, mollusks, crustaceans, and worms

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FYIPearls

• Many species of bivalves produce pearls
• When a grain of sand becomes stuck between a
  mollusks mantle and shell, the mollusk coats the
  sand with nacre
• Nacre is also mother-of-pearl that is also used
  on the inside of the bivalves shell
• The sand is continually covered in nacre to form
  a pearl
• Only pearls that contain overlapping mineral
  crystals within the nacre are considered
  gem-quality pearls

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Phylum Arthropoda

• FYI Means jointed foot
• FYI Over 1 million species
• Most diverse group of animals
• Most have
• Segmented bodies
• Usually in three distinct regions head, thorax
  (mid-body region) and abdomen
• The head may fuse with the thorax to form a
  cephalothorax
• Exoskeleton made of protein, chitin
• Prevents water loss, protects internal
  structures, and attachment for muscles
• Does not grow with organism, so they must shed
  their exoskeletonmolting

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More common characteristics

• Appendages legs, antennae, mouthparts etc that
  grow out from the body and are jointed/bendable
• Open circulatory system
• Air enters spiracles through a network of fine
  tubes called tracheae
• Distinct head often with compound eyes
• Eye made of thousands of individual units each
  with its own lens and retina
• Image is not as clear but motion is detected more
  quickly

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Chelicerata

• Spiders, scorpions, ticks, mites, marine
  horseshoe crabs, sea spiders, and harvestman
  (daddy long legs)?

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Chelicerata

• Chelicerae are mouthparts modified into fangs
• Arachnid body
• Cephalothorax
• Abdomen
• No antennae
• Chelicerae, first pair of appendages
• Second appendage, pedipalps modified to catch and
  handle prey
• Four functioning legs
• All arachnids are carnivorous except mites
• Spiderproduce silk through spinnerets
• Scorpionsstinger-tipped abdomen
• Mitessingle, unsegmented body

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Crustaceans

• Crabs, lobsters, crayfish, shrimps, barnacles,
  water fleas, Daphnia, pill bugs, etc

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Crustaceans

• Gills
• Cephalothorax with protective shieldcarapace
• In crayfish and lobsters, anterior pair of legs
  is modified into large pinchers called chelipeds
• Barnacles are sessile crustaceans with a
  free-swimming larval stage
• Reproduction mainly sexual with internal
  fertilization
• Sperm is deposited where eggs are released, no
  water required

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Uniramia (Insecta, Diplopoda, Chilopoda)?

• Butterflies, beetles, fleas, lice, grasshoppers,
  ants, mosquitoes, etc

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Insecta

• Chewing mouthpartsmandibles
• Most have
• Head-mandibles, one pair of antennae, compound
  eyes
• Thorax-composed of three fused segments, two or
  three pairs of jointed legs attached
• Abdomen-composed of 9-11 segments
• First animals to evolve wings
• Insect life cycle
• Complete metamorphosis
• Egg, larva, protective capsule stage chrysalis,
  pupa, adult
• Incomplete metamorphosis
• Egg, nymph, after several molts becomes adult

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Developmental Patterns

• Protostomesdevelop a mouth first and anus second
  from the opening of the digestive cavity
• Nematodes, Annelids, Mollusks, Arthropods
• Deuterostomesdevelop an anus first and a mouth
  second
• Echinoderms

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Phylum Echinodermata- Sea stars, sand dollars,
sea cucumbers, sea urchins

• Spiny skin
• All marine
• Bilateral larvae then 5-part radial symmetry as
  adults
• Number of arms can vary

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• Calcium-rich endoskeleton composed of individual
  plates called ossicles
• Even though the ossicles of adult echinoderms
  appear to be external, they are covered by a thin
  layer of skin
• No head or brain
• Nervous system consists of a central ring of
  nerves with branches extending into each of the
  arms
• Regeneration of arms
• Water vascular systemwater-filled system of
  interconnected canals and thousands of tiny
  hollow tube feet
• Tube feet extend outward through openings in the
  ossicles
• Used for locomotion, feeding and gas exchange

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• Sea stars
• Most are carnivores
• Responsible for the mass destruction of coral
  polyp colonies
• Brittle stars
• Name given for the delicacy of their brittle arms
• Most are filter feeders
• Sea lilies and feather stars
• Most ancient and primitive echinoderms
• Sessile

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• Sea urchin and sand dollars
• Lack arms but still have the 5-part body plan
• Some sea urchins contain venom
• Sea cucumbers
• Soft-bodied, slug-like animals without arms
• Ossicles are small and not fused
• Sea daisies
• Only two known species of newly discovered group
• No arms but still have 5-part radial symmetry