most animals (>95%) are inverts aside from very successful insects, most animals are marine
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Kingdom Animalia – all animals are multicellular heterotrophs that lack cell walls and share the first few steps of early embryology
Animals are very diverse in form, organization, and complexity from the simplest invertebrates to more complex vertebrates
– Most animals (>95%) are inverts– Aside from very successful insects, most animals are marine– Diverse morphologies, habitats, and adaptations
• Prokaryotes– Domain Bacteria– Domain Archaea
• Eukaryotes– Domain Eukarya
• Kingdom Protista• Kingdom Plantae• Kingdom Fungi
– Chytridiomycota
– Phylum Zygomycota
– Phylum Basidiomycota
– Phylum Ascomycota
• Kingdom Animalia
• Kingdom Animalia– Phylum Porifera– Phylum Cnidaria– Phylum Ctenophora– Phylum Platyhelminthes– Phylum Nemertea– Phylum Nematoda– Phylum Rotifera– Phylum Mollusca– Phylum Annelida– Phylum Arthropoda– Phylum Echinodermata– Phylum Chordata
Phylum Porifera
• Sponges• Habitat
– Mostly marine, few freshwater
– sessile
• Suspension filter feeders• Cellular level (lacks true
tissues and organs)• Body plan = asymmetrical
Although sponges lack true tissues they still carry out specific functions – at the cellular level
– Porocytes: water canal– Pinacocytes: flat protective cells– Choanocytes: “collar cells” capture food (plankton)– Amebocytes: transport food; differentiate into other cells– Spicules: siliceous or calcareous skeletal structures
Poriferan body plans
Sponges, like many organisms, can reproduce asexually and sexually. – Asexual budding– Sexual broadcast spawn
Sponges, as simple as they are, show diverse adaptations and organization to varied environments
Examples of these varied body plans include:– Tropical to temperate encrusting– Subtropical bath sponges– Deep water glass sponge
Phylum Cnidaria (nigh-dare-ia)
Are nearly all marine and include jellyfish, sea anemones, & coral which all share radial symmetry and specialized cells for predatory feeding
Cnidarians are at the tissue level of organization…yet only two true derived tissues.
• 2 layers– Epidermis and gastrodermis– Mesoglea is middle jelly layer
rather than a true tissue
Closer, but not yet…• Recall: Gastrulation (Infolding of
the blastula)• Forming a primitive gut &
embryonic tissues– Endoderm lining of
gut/organs
– Mesoderm muscle, bone, connective tissue
– Ectoderm skin, hair, nails, nervous tissue
Cnidarian gut is described as gastrovascular cavity w/extracellular digestion
Cnidarians exhibit two basic body forms: medusa (swimming) and polyp (attached)
Furthermore…• Polyp forms can be
either solitary (individual polyps) or colonial (integrated of many polyp types)
• Cnidarian life-cycles can include alternations of medusa and polyp generations.
Phylum Cnidaria is organized into 4 classes:
• Class HydrozoaGreek: multi-serpent-headed water beast
– Individual polyps
– colonies of specialized polyps
• Feeding• Reproductive• Defense
Sessile colonies
Drifting colonies
• Class Scyphozoa with dominant medusae stage– Examples
• Sea Nettle• Moon Jelly• Upside-down Jelly
• Class Cubozoa– Tropical– Potent toxins
Class Anthozoa• Solitary or colonial
polyps w/out medusae stage– Sea anemones
• Some with zooxanthellae symbionts
– Photosynthesizing protists
– Corals• CaCO3 skeletons• Environmentally valuable
reefs• Extremely susceptible to
negative impacts– Pollution, increased
temp., etc
Phylum Ctenophora
Comb jellies• Marine planktonic
predators that use 8 rows of ciliary combs or ctenes to swim
• Instead of cnidocytes, have tentacles with colloblasts to capture prey– Adhesive, non-stinging
cells
Phylum Platyhelminthes
Flatworms• Bilateral symmetry• Organ level
– Except no circulatory
• Cerebral ganglia– Simple brain
• Reproduction:– Asexual (simple regeneration)– Sexual
• Most are hermaphrodites
• Include free-living (self foraging) & parasitic lifestyles
Flatworms have 3 distinct tissue layers – gave rise to a more complex digestive system
• This closed digestive system is described as an incomplete gut rather than a complete gut
• Acoelomic (w/out coelom or protective gut cavity)
Parasitic flatworms find a host to feed from than spend much of their resources on reproduction
Chinese liver fluke - Opisthorchis sinensis
Opisthorchis lifecycle
Schistosoma
Female
Similar to this mammal tapeworm example, marine tapeworms are internal parasites to fish and marine mammals.“…as dense as seaweed forests, that live in the guts of sharks.”
Cestoda
Cestoda scolexes
Cestode proglottid 2
Testes
Ovary
Yolk gland
Phylum Nemertea• Ribbon worms
“not flat, nor round”• Advanced organ system
over flat worms– Circulatory system
– Complete gut
– Between Acoelomates & Pseudocoelomates
• Rhynchocoel: partial cavity around proboscis
• Eversible proboscis
Phylum Nematoda• Roundworms
Bit more space for more complex development
• Complete gut• pseudocoelomates• Varied environments,
size, & lifestyles– Aquatic to terrestrial– Free-living to parasitic
• Marine sediments (feed on bacteria)
• Parasitic to most marine animals & many others
• Reproduction – Primarily sexual
One of the biggest marine parasites measures 13 meters and is two centimeters in diameter …found in the placenta of the sperm whale.
Trichinella
Enterobius
female
Ascaris
Censored
Ascaris female x.s.
Ascaris male x.s.
Phylum Rotifera• Microscopic, yet
multicellular, organ-level aquatic animals
• Ciliated crown (“wheel”) to funnel food
• Pharyngeal grinding structure (mastax)
• Complete gut• Pseudocoelomates• Reproduce
– Sexually …or… – Parthenogenesis (“virgin birth”)
• Females eggs female offspring (w/out fertilization)
Phylum MolluscaVery diverse group of soft body inverts
that include Gastropods (Snails, slugs), Bivalves (oysters, clams, mussels), and Cephalopods (squid, cuttlefish, octopus)
• examples within this phylum are found in diverse environments: Marine, freshwater, moist land
and, share characteristics such as…• Open circulatory system
– central blood cavity rather than highly branched blood vessels
• Mantle for protection– Secretes shell, provides space for gills
and siphons• Locomotive muscular “foot”• Well developed Nervous system
…in most
Class Gastropoda• “stomach footed”• Mantle
– Tissue that secretes shell
• Radula– Rows of rasping
teeth for grazing– Modified in
predators
Cone shells• Single harpoon
tooth – evolved from rowed
ancestors– filled with paralyzing
venom
• Conotoxins– Medical value for
specific neural & muscle treatment
– Addictive-free pain killers
Class Bivalvia
• Clams, oysters, mussels…
• Suspension filter feeders– Incurrent & excurrent
siphons
• Spade-foot for locomotion
• Two valves (shells) secreted by mantle– Held closed by
powerful adductor muscles
• Class Polyplacophora– Chitons
• Graze on microalgae• 8 overlapping plates
• Class Scaphopoda– Tusk shells
• Open at both ends• Deeper benthic
sand/mud
Class Cephalopoda
• Squid, octopus, cuttlefish, nautilus
• Shell: internal, external, or lacking
• Well developed nervous system
• Most adapted for active predatory lifestyle
Class Cephalopoda (cont.)• Muscular foot modified to
arms &/or tentacles– Siphon for locomotion
• Hydropropulsion
• Ink sac or gland– defense
• Chromatophores– Adjustable pigment cells
• Conotoxins in some
Reproduction
• Most are separate sexes
• Some free spawners– bivalves
• Most develop from:– Trochophore larva
• Ring of cilia
– Veliger larva• Ciliated mass
• Some parasitic larva– Glochidia larva of some fresh water clams
Phylum Annelida• Segmented worms
– Earthworms– Polychaetes– Leeches
• Repetitive body parts• Hydrostatic skeleton
– Flexibility and strength• Coelomates • Longitudinal & circular muscles• Closed circulatory system• Excretory organs• Marine, moist land, and some
freshwater• Bilateral symmetry• Some parasitic
Earthworm dissected
Nereis• Class Polychaeta• Adaptations to
predatory lifestyle– Eyes, tentacles, jaws,
etc
• Coelom– Protective gut cavity
• Parapodia– w/setae– Respiratory, nervous,
and locomotion
Phylum Annelida
• phylogenetically placed between Mollusca and Arthropoda– Trocophore larva – segmentation
Phylum Onychophora
• “walking worms”
… or velvet worms– Tropical predator
• Link between annelids and arthropods– Walking appendages– Lacks exoskeleton– Antennae– Soft segmented body,
yet chitinous– Arthropod-like
circulatory system
Phylum ArthropodaExamples (whether aquatic or
terrestrial) include Insects, spiders, crabs, shrimp, centipedes – all of which possess a hard chitinous exoskeleton– Replaced via molting
• Jointed bilateral appendages• Segmented body• Open circulatory system• Many marine crustaceans
– Two pairs of antennae– gills
Subphylum Trilobita
Subphylum Chelicerata
• Chelicera– First pair of oral
appendages• Scorpion pinchers• Spider fangs
• Lack antennae• Book gills or book
lungs• Typically four pairs
of walking legs• 2 body regions
– Cephalothorax & abdomen
Class Merostomata
Class Arachnida
Order Scorpiones
Order Uropygi
Order Aranae
Order Opiliones
Order Acari
Order Acari
Subphylum Crustacea
• Includes: fairy shrimp, copepods, barnacles, decapods (shrimps, lobsters, crabs), isopods, and amphipods
• Two body regions– Cephalothorax & abdomen
• Two pairs of antennae• At least 4 prs of walking
legs
Class Branchiopoda
• “gill feet”• Many thoracic
appendages– Swimming– …and modified as gills
• Primarily freshwater• Examples
– Fairy shrimp– Water flea
Class Copepoda• Very abundant plankton• Biramous appendages• Long first antennae
Class CirripediaBarnacles• Suspension feeders
– Cirri (also for respiration)
• Protected by calcareous plates
• Free-swimming larvae– Nauplius
Other Crustaceans… Class Malacostraca Order Decapoda
• Shrimps, crabs, lobsters…
• 5 pairs walking legs– Thoracic pereopods– 1st pr as cheliped
• 5 pairs abdominal appendages– Pleopods or
swimmerets
Crayfish dissection
Order Amphipoda & Order Isopoda
• Laterally flattened• Shrimp-like
• Dorsal-ventrally flattened
Subphylum Uniramia
• Unbranched appendages• Or… 2 Subphylums:
– Myriapoda– Hexapoda
• Class Insecta• Very diverse and abundant• Head, thorax, abdomen• Compound and simple
eyes• Spiracles rather than lungs
– Open canals – “ram respiration”
Development & Metamorphosis
Feeding maggot larval stage; pupa; adult
Gradual development sub-adults to adults
Order Anoplura (head louse and nit)
Anoplura (crab louse)
Order Coleoptera
• Beetles• Sheath wing
– Forewings hard and leathery– Hindwings membranous
Order Dermaptera
• Earwigs• “skin-fasten”
– Ear shape of hindwing
• Are not known to crawl into ears
Order Diptera
• Flies; mosquitos• Dominant forewings• 2nd pair very different
– Reduced to tiny halters or vibrating balancers
– For equilibrium
Order Hymenoptera
• Bees; wasps; ants• “membrane-wings”
– Hindwings reduced and attached to 1st
• Male ants keep wings, mate with queen
• Female ants are wingless, sterile, workers
Order Hemiptera
• True bugs– Stink bugs;
waterstriders
• “half-wing”– Forewing is leathery
in the front but membranous in the rear
Order Homoptera
• Aphids; leaf hoppers; cicadas
• “same-wings”– Both pairs
membranous– Folds parallel over
abdomen
Order Isoptera
• Termites• “equal-wing”
– 2 pair of equal size– Lost at maturity
Order Lepidoptera
• Moths and butterflies
• “scaly or rough-wing”– 2 pair covered in
scales
Order Odonata
• Dragonflies and damselflies
• 2 pr elongated membranous wings– perpendicular to
thorax– parallel to thorax
• Dominant aquatic nymph stage (“see-swimming)
Order Orthoptera
• Grasshoppers; crickets; cockroach; praying mantis
• “straight or correct-wing”– Forewings leathery
Order Siphonaptera
• Fleas• Wings absent• Piercing/sucking
parasitic mouthparts
Subphylum MyriapodaClass Chilopoda & Diplopoda
• Centipedes• 1 pair of appendages per
segment• Dorso-ventrally flattened• Predatory lifestyle
• Millipedes• 2 pair of appendages per
segment• Circular rather than flattened• Herbivorous
Deuterostomes• Anus first, mouth second• Radial cleavage• Enteroceoelous rather than
schizoceolous• Indeterminate blastomeres• Ventral heart• Dorsal nerve cord
Phylum Echinodermata“Spiny skin”• All marine; mostly benthic
(sea floor)• Radial symmetry• Some regenerate asexually• 5 classes
– Crinoidea--feather stars and sea lilies
– Asteriodea--sea stars – Ophiuroidea--brittle stars and
basket stars– Echinoidea--sand dollars and
sea urchins– Holothuroidea--sea
cucumbers• Water vascular system
– Tube feet
Lophophorates• Lophophore =
unique ciliated feeding structure
• Bryozoans– Colonial moss
animals– Secrete CaCO3
• Brachiopods– Two valves (shells)
• Chaetognaths– Lophophore
modified– Aggressive pelagic
predators• (plankton)
Phylum ChordataInvertebrate chordates examples
– Subphylum Urochordata• Tunicates, sea squirts, ascidians
– Subphylum Cephalochordata• Lancelets
Share 4 “chordate” characteristics• Notochord
– Flexible rod-like structure
• Dorsal nerve cord– Tube for nerves
• Pharyngeal gill slits– Respiration and feeding
• Post-anal tail– Reabsorbed in some species
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