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Unit 1: Taxonomy and
Invertebrates
8 days
August 4th: Introduction to Veterinary
Science
Welcome Back!
Grading Policy
Units
Excursion Learning
Tests
Website
Labs
Class Rules
August 5th: Cladistics and Taxonomy
Why is classification necessary?
How do we classify organisms?
D
K
P
C
O
F
G
S
Cladistics
Taxonomy
Phylogenetic Tree of Life
Dichotomous Keys
August 6th: Kingdoms, Animals
• What is an animal?
Eukaryotic
Multicellular
Motile
Heterotrophic
Heterotrophic
No cell walls
Blastula Phase of Development
Invertebrates
• Animals that are typically small, and do NOT
have a backbone
• Immensely varied,
account for 97% of
all known animal
Species
• Occupy more than 30 phyla
Evolution
• Invertebrate were originally soft bodied, and
left indirect signs of existence such as tracks
and burrows
• Date back ~1 billion
years
• Cambrian Explosion
(600 mya)
Trilobites
• Extremely successful
• Lived for ~300 my
• Died out ~245 mya
Invertebrate Analysis
Pay attention to:
Skeleton
Symmetry
Senses
Reproduction
August 11th: Porifera
• What is a sponge?
• About 10,000 species
• Mostly marine, about 150 freshwater
• Originally classified as plants
General Characteristics
Have pores, filter water
Particles enter cells through phagocytosis
Asymmetrical or radial symmetry
Skeleton made from collagen
Cells are called spicules
Silicon dioxide or
Calcium carbonate
Filter Feeders
General Characteristics
Reproduction can be sexual and/or asexual
Asexual = budding
Sexual = release gametes into water current
Blastula formation
Larvae may settle almost instantly, or become planktonic
General Characteristics
Sessile as adults
No nervous tissue
Few muscle cells
Multicellular
Have cell differentiation
Not organized into tissues
Porifera Anatomy
Classification
Kingdom: Animalia
Phylum: Porifera
Class: Calcarea
Calcareous Sponges:
~100 species
Shallow water, crevices, in caves, on seaweed
Spicules made of calcium carbonate
Generally small and drab
Classification
Kingdom: Animalia
Phylum: Porifera
Class: Hexactinellida
Glass Sponges:
~500 species
Cold water, very deep (650 – 6,600 ft)
Spicules fused together to form beautiful glass-like masses
Delicate, and often damaged when brought up from depth
Classification
Kingdom: Animalia
Phylum: Porifera
Class: Demospongiae
Demosponges:
~9,500 species
Shallow and deep water, on solid surfaces
Often brilliantly colored
Varied in size and shape
August 12th: Cnidaria and
Echinodermata
• What are cnidarians?
• Jellyfish, corals, hydra, sea anemones
• About 8,000 species
• Mostly marine, a few found in freshwater
General Characteristics
Radial or biradial symmetry
Have tissues
No organ formation
Have digestive systems
Two way
Have nervous system
‘nerve net’
Body Forms
Reproduction
• Sexual or Asexual
Asexual = Budding
Sexual = formation of
free swimming larva
Individuals become either
monoecious or dioecious
Special Adaptations
Nematocysts
Special Adaptations
Reef Building
Special Adaptations
Locomotion
Use water filled cavities to contract muscle
against and allow movement.
Medusa swim using weak jet propulsion
Polyps bend, lengthen, or shorten their body
Classification
Kingdom: Animal
Phylum: Cnidaria
Class: Anthozoa
Sea Anemones and Corals:
~6,500 species
‘antho’ = flower, ‘zoa’ = animal
Colorful
Carnivorous, some algae symbiosis
Classification
Kingdom: Animal
Phylum: Cnidaria
Class: Scyphozoa
Jellyfish:
~250 species
In marine plankton
Can be up to 2m across, and have feet of tentacles
Complex lifecycle – polyps are asexual, and medusa are sexual
Examples: Moon Jelly, Sea Wasp, Lion’s Mane Jellyfish, Upside Down Jelly
Classification
Kingdom: Animal
Phylum: Cnidaria
Class: Hydrozoa
Hydrozoans:
~3,300 species
Plankton, sea, river, and lake beds
Colonial – often with polymorphic polyps
Mistaken for coral and/or jellyfish
Examples: Portuguese Man-Of-War, Aglaophenia (feather hydroids), Hydra,
Tubularia, Hydractinia, Velella velella
Echinodermata
• What is an echinoderm?
‘echino’ = spiny, ‘derm’ = skin
~6,000 species
~13,000 extinct species
Marine , no freshwater species
General Characteristics
• Evolved from sessile ancestors
• Pentaradial symmetry
• Water vascular system
• Complete digestive system
• Nervous system
General Characteristics
• Calcareous internal skeleton
• Sexual reproduction, spawning
• Spines for protection,
may be poisonous
• Mostly motile
Echinoderm Anatomy
Classification
Kingdom: Animal
Phylum: Echinodermata
Class: Crinoidea – sea lilies (630 sp)
Class: Asteroidea – starfish (1,500 sp)
Class: Ophiuroidea – brittle stars (2,000 sp)
Class: Holothuroidea – sea cucumbers (1,150 sp)
Class: Echinoidea – sea urchins (975 sp)
Echinoderm
Pictures
Echinoderm
Pictures
August 13th: Platyhelminthes and
Nematoda
• What is a worm?
• Divided into 3 phyla.
Platyhelminthes
• Also called Flatworms
• ~13,000 sp
General Characteristics
• Bilateral symmetry
• No internal cavity
• No circulatory system
• No respiratory system
• Often parasitic
General Characteristics
• 2 way digestive systems
• Longitudinal nerve fibers
• Mostly sexual
• Mostly hermaphroditic
Platyhelminthes Anatomy
Classification
Kingdom: Animal
Phylum: Platyhelminthes
Class: Turbellaria
Turbellarians:
+4,000 sp
Damp soil, under logs
Some free living marine species are brightly colored
Usually thin to allow diffusion of oxygen
Classification
Kingdom: Animal
Phylum: Platyhelminthes
Class: Cestoda
Tapeworms:
~3,500 sp
All parasitic
Most live within cartilaginous fish
Can be up to 100ft long
Form segments called proglottids
Each proglottid houses a complete reproductive system and thousands of eggs
Classification
Kingdom: Animal
Phylum: Platyhelminthes
Class: Trematoda
Flukes:
~12,000 sp
All parasitic
Sexual dimorphism
Have mouths and digestive systems
Complex lifecycles, often pass through mollusks and end in vertebrates
Platyhelminthes Pictures
Nematoda
• What is a nematode?
• Among the most abundant of all animals
• Live inside almost every animal and plant
General Characteristics
• Round cross section
• Shed complex cuticle
4 times during lifespan
• Tapered at each end
• Move by thrashing (form C or S shapes)
• Bilateral symmetry
General Characteristics
• Have complete digestive system
• Have nervous system
• No circulatory system
• Usually sexual
• Often parasitic
Nematode Anatomy
Classification
Kingdom: Animal
Phylum: Nematoda
Class: Secernentea
Secernenteans:
~8,000 sp
Vary greatly in size
Largest is 30ft long found in sperm whale placenta
Can also be microscopic
Can be very harmful as in Elephantiasis
Classification
Kingdom: Animal
Phylum: Nematoda
Class: Adenophorea
Adenophoreans:
~12,000 sp
Live everywhere except deserts
Mainly free living
Can be pathogenic, like Trichinella spiralis
August 14th: Annelida and Mollusca
• What is a segmented worm?
• ~9,000 sp
• Mostly aquatic, though a few terrestrial
species are well known
General Characteristics
• Bilateral symmetry
• Complete digestive system
• Nervous system including anterior nerve ring
• Have closed circulatory systems
• No respiratory organs
Reproduction
• Usually sexual or hermaphroditic
Annelida Anatomy
Locomotion
Annelids move
by wave motion,
using their
longitudinal
and circular
muscles
Classification
Kingdom: Animal
Phylum: Annelida
Class: Polychaeta
Bristleworms and Tubeworms:
~8,250 sp
Usually sexual
Ex. Fanworms, Parchment worms,
Ragworms, Sea mouse
Classification
Kingdom: Animal
Phylum: Annelida
Class: Clitellata
Clitellates:
~6,000 sp
Have clitellum
Hermaphroditic
Lack head appendages
Ex. Earthworms, leeches
Mollusca
• What is a mollusk?
• ~110,000 sp
• Widest range of body types of all invertebrates
General Characteristics
• Size ranges widely
• Often secrete shells
• Bilateral symmetry
• Have complete digestive system
Use radula to rasp prey and collect small particles of food
General Characteristics
• Have nervous system
• Open circulatory system
with heart
• Have gills
• Sexual and often hermaphroditic
Locomotion
• Use foot to creep along
• Use fins to swim
• Use jet propulsion
Classification
• Three main types:
– Cephalopods
– Gastropods
– Bivalves
Cephalopod Anatomy
Gastropod Anatomy
Bivalve Anatomy
August 18th: Arthropoda
• Largest phylum of living organisms
• Account for 3 out of 4 known species of animals
• ~1.1 million species
General Characteristics
• Estimated 30 million unnamed species
• Extremely important ecologically
• Decomposers and pollinators
• Very diverse in form and habitat
General Characteristics
• Bilateral symmetry
• Exoskeleton
• At least 2 body segments
• Nervous system with brain
General Characteristics
• Open circulatory system with heart and
arteries (no veins)
• Complete digestive system
• Respiratory system, often with trachea
• Usually sexual
Subphylum: Crustacea
• 2 pairs of antennae
• Have biramous limbs
• Smallest subphyla of
arthropoda
Crustacea Anatomy
Crustacea Pictures
Subphylum: Uniramia
• 3 pairs of legs (usually)
• Have 3 or more body segments
• Includes:
– Insects
– Centipedes
– Millipedes
Uniramia Anatomy
Uniramia Pictures
Subphylum: Chelicerata
• Have 4 pairs of legs (usually)
• Have book lungs
• Includes:
– Scorpions
– Spiders
– Mites
– Horseshoe crabs
Chelicerata Anatomy
Chelicerata Pictures