Unit 1 Animal Diversity
Intro
-32 major phyla
-cambryan explosion 600 mya
-most major body plans evolved
-despite evolutionary pressure, forms limited by ancestral archetypes
Body Plans of Animals
-categoized by features of morphology
Grade
-group of species that share the same level of organizational complexity
5 Different Grades (Levels of Organization)
-cells (most simple)
-tissue
-organ
-organ system
-organisim (most complex)
Protoplasmic (Hierarchial Levels of Complexity)
-NOT ANIMALS
-unicellular organisims
-protists (simplest eukaryotes)
-carry out all life functions amongst single cell structures
Cellular (Hierarchial Levels of Complexity)
-metazoans are multicellular animals
-have specalized structures for particuar functions
-spongrs are simplest metazoans
Cell-Tissue (Hierarchial Levels of Complexity)
-tissue is specalized cells grouped together to form as. a coordinated unit
-EX; jellyfish
Tissue-Organ (Hierarchial Levels of Complexity)
-tissues are assembled into organs
-connective, epithelial, muscle, nervous
-EX; heart=muscle
Organ (Hierarchial Levels of Complexity)
-highest level of organization
-organs work together for a common function
-basic body functions, circulation, respiration, digestion
Animal Body Plans
-ABP's differ by:
grade/organization
body symmetry
# of germ layers
type of body cavity
Radial Phyla
-more than 2 planes can divide an organisim into similar halves
-phylum Cnidaria and Ctenophora
-no front or back
-interact with their environment from all directions
-weak swimmers
-EX; jellyfish, sea anenomes, coral
Bilateral Symmetry
-organisims with 1 plane that divides the organisims intoo similar halves (left & right)
-better for directional movement (forward)
Cephalization
-differentation of a head
-bilateral symetry is associated with cephalization
-moving in head first directional movement
-nervous tissue (increasing brain size)
-sense organs respond to environment
Transverse Plane
-crossection
-anterior/posterior division
Frontal Plane
-dorsal/ventral division
-front/back
Saggital Plane
-right and left halves
Body Cavity
-internal space
-3 body plans possible
Aceolomate
-no body cavity
Psuedoceolomate
-body cavity between endoderm and mesoderm
-not completely lined with mesoderm
Coelomate (Euceolomate)
-body cavity surrounded by mesoderm
Blastula Stages
-sponges develop only to blastula stages, then reorganize to form adult
*lack tissues
Gastrulation
-allows animals to proceed to tissue level organization
*germ layer=tissue layer
Diploblast
-2 germ layers
-EX: cnidaria, ctenophora
Triploblast
-3 germ layers
-has mesoderm
-everything else (besides cnidaria & ctenophora)
Endoderm
-innermost layer
Mesoderm
-middle layer
Ectoderm
-outermost layer
Blind Gut
-In some organisims the gut does not form a complete tube
-waste comes back out of mouth
Alimentary Canal (Complete Gut)
-a complete gut forms a tube within a tube body plan
Segmentation (Metarisim)
-serial repetition of similar body segements)
-greater mobility
-more complex structure and function
-EX: annelida (earthworm), arthropoda (segmented legs of lobster), chordata(ribs of fish)
Tissue Structure and Function
-tissue is a group of similar cells specalized for performing a common function
-cellular components
-tissues are classified into 4 main categories (epithelial, connective, muscle, nervous)
Complexity and Body Size
-increased complexity allows fo an increase in body size
-larger size decreases the surface area to volume ratio
-cost of maintaining body temp is less per gram of body weight than in small animals
-energy costs of moving a gram of body weight over a given distance is less for larger animals
*how animals develop is used to determine their evolutionary history and classify them into groups
Evolution and Diversity
-more than 2.5 million species of animals named
-animall diversity is not random and has definite order
-natural system of order refects relationships among animals in nature
-darwin's theory of evolution is a guide
-principle of natural selection
Taxonomy
-a formal system for naming and classifying species following the principle of common. descent
Animal Classification
-animals with a recent similar ancestry are grouped together
-organized in nested hierarchy of groups within groups on shared features
-many flaws, can be cntriversal
-"artifical" (humans made it up)
Goals of Systematic Zoologists
-discover all species of animals
-to reconnect their evolutionary relationships
-to classify animals according to their evolutionary relationships
Systematics (Comparitive Biology)
-classifiying organisims based on studies of variation among populations that reveal their evolutionary rlationships
Linnaeus and Taxonomy
-aristotle was the first to classify organisims
-carolus linnaeus was a swedish botanist who designed the current classification system
-binomial system of nomenclature (2 word scientific names)
-organized: class (largest) > order > family > genus (smallest)
Taxonomic Ranks
-taxa=major animal groups at each level of the hierarchy
-kingdom (largest 2.5 mill) > phylum > class > order > family > genus > species (smallest 1)
-all anials are placed in kingdom animalia
-each major rank can be further subdivided into smaller levels of taxa such as superclass
Classification
-determines if the species has defining features
Systemization
-places groups of species into units of common evolutionary descent
Binomial Species Nomenclature
-2 words written in italics
-unique to each species
-genus capitalized(noun)
-specific epithet lowercase (adjective)
What Determines a Species
-common descent
-smallest distinct grouping
-reproductive community (sexual)
Common Descent (Common Ancestor)
-central theme to all modern concepts of species trace their ancestry to a common ancient population but not necessarily the same exact pair of parents
Smallest Distinct Grouping
-species must be the smallest unit sharing unit sharing patterns of ancestry and descent
-morphology has been traditionally used but now is supplemented with chromosomal and molecular characteristic (RNA & DNA)
Species Distribution
-all species differ greatly in their distribution yhrough space and time
-geographic range
Cosmopolitan Species
-having a very large geographic range or potentially a worldwide distribution.
Evolutionary Duration
-distribution throught time which is variable to species
Endemic
-species with very restricted geographic distributons
Biological Species Co-Concept
-Mayr 1940
-a species is a reproductive community of populations reprductivally isolatyed from eachother
Phylogenetic Species Concept
-Joel Cracaft
-a basal grouping of organisims diagnosably distinct from other such groupins and whithin which there is a parental pattern of ancestry and descent
-single population with no branching
-recognizes sexual and asexual reproduction
-emphasizes common descent
does not allow for future merging of populations
Phylogeny
-evolutionary tree that relates all extent and extinct species
Character
-identifies all features that vary among species
Ancestral Character
-present in the most recent common ancestor
Derived Charcters
-different states of the charachter that arose later
Homology
-character from common ancestry
-EX: bird wings and people arms
Homoplasy
-non homologus similarity, independent evolutionary origin
-EX: body heat in birds and people, common trait but unrelated
Analagous
-characters with similar function
-EX: octopus arms, grasshopper legs, sea star legs
Clade
-a unit of evolutionary common descent that includes ancestry lineage and all descendants
Cladogram
-nested hierarchy of clades presented as a branching diagram
-not similar to phylogenetic trees which represent real lineages in evolutionary history
-normally act as the first approximation of the branching stretch
Derived Character State
-all other character forms arose later
Polarity of Character
-identifying which of the contrasting states (present vs absent) is ancestral
Monophyly
-a monophyletic taxon includes the most recent common ancestor and all descendents of that ancestor
Paraphyly
-a taxon is paraphyletic if it icludes the most common ancestor of all members of a group and some but not all decendants of that ancestor
Major Divisions of Life
-cladistic classification of all life forms based on phylogenetic information from DNA
Monophyletic Domains
-eukarya (all eukaryotes, eukaryotic cells)
-bacteria (prokaryotic cells, lack nucleus)
-archea (prokaryotic cells, lack nucleus)
Origin of Multicellularity
-cells are the elementary units of life
-increasing the size of a cell causes problems exchaning molecules with the environment
-multicellularity prevents surface to mass problems
-greater increase in surface area = greater metabolic activities
-highly adaptive towards larger body size
Origin of Metazoa
-evolution of the eukaryotic cell was followed by diversification into many different lineages (modern protozoans, plants, fungi, animals)
Metazoans
-multicellular animals
Choanoflagellates
-kingdom protista (not animals)
-colonial or solitary protozoans with a flagellum surrounded by a collar of microvilli
-sister group to metazoans
Sponges
-sponges are sessile animals
-have a porous body
-range in size and shape up to 2 meters in diamater
-encrusting, boring, finger, tube, or vase shaped
-they live in both fresh and marine waters
Phylum Porifera
-multicellular, cells differentiate for different functions
-no organs or true tissues
-lack nervous system
-porous body
-lack of symmetry
-exhibit both sexual (eggs and sperm) and askexual (buds and gemmules) reproduction
-mostly marine, all aquatic
Skeletal Framework
-sponges DO NOT have a true skeleton
-the skeletal framework of a sponge may be fibrous or rigid
-sponges classified by skeletal structure
-the fibrous part comes from collagen fibrils
-rigid, made of needlelike spicules
-calcerous, siliceous
Chonaocytes
-sponge feeding cells
-flagellated collar cells
-generate a water current through the sponge and ingest suspended food
Pinacocytes
-thin, flat, epithelial cells that cover the exterior and some interior surfaces of the sponge
-incipient tissue
Archeocytes
-ameboid cells that move in the mesophyll and can recive food particles for digestion in the sponge
-can differentiate into other functional cell types
Suspension Feeders
-capture food particles that pass through their bodies
-water flows past choanocytes where the food particles are collected on the choanocyte collar
Fragmentation
-asexual reproduction
-parts capable of becoming new sponge after being broken off from main body
Internal Buds (Gemmules)
-asexual reproduction
-similar to fragmentation
-in freshwater sponges, can remain dormant in times of drought
Sexual Reproduction
-most sponges are monoecious (hermaphrodites)
-gametes are drived from choanocytes and sometimes archeocytes
-sperm released into water, after fertilization the zygote is retianed and nourished by parent
-cilliated larve are later released
-some species release both sperm and oocytes into water
Phylum Placozoa
-Trichoplax adhaerens is the sole species in phylum placozoa
-simple blob like creatures
-marine
-no symmetry
-no muscular system, nervous system, or organs
-placozoans glide over food, secrete digestive enzymes, and absorb nutrients
-almost fungal like
-a cross between a sponge and a sand dollar
Phylum Cnidaria
-over 9,000 species
-soecalized cnidocyte cells that contain nematocysts (stinging organelles)
-some are symbiotic with alge which are critical for reef building corals
-cnidarian fossils dated over 700 mya
-jellyfish, coral
-have a nerve net (not a nervous system) impuses starting in one part are conducted in all directions. no one way direction
-DO have tissues
Cnidocytes (Stinging Cells)
-cnidarians are effective predators
-cnidocytes are invaginations of the ectodermal cells
-nematocysts- tiny capsules contain a coiled fillament
-they may have barbs or spines
-venom may be injected when it enters prey
Polyp
-adaped to be sedentary
-mouth is upward facing and surrounded by tentacles
-reproduce asexually by budding, fission, or pedal laceration
-in colonies can specalize defense, feeding (hydraths) or reproduction (gonangia)
Medusa
-free swimming
-bell shaped
-downward facing mouth, tentacles extend downward
-have statocysts to detect orientation and ocelli to detect light
-reproduce sexually
Hyphozoa
-hydroids
-fire corals
-portugese man-o-war
Scyphozoa
-true jellyfishes
Anthozoa
-largest class
-"flower animals"
-solitary or colonial
-some having a hard skeleton
-includes stony corals
-soft corals
-sea anenomes
Coral Reefs
-great diversity of organisims
-one of the most productive ecosysyems, rivaled only by tropical rain forests
-formed mostly by scleractinin hermatypic (reef building) corals and coraline alge
Phylum Ctenophora
-comb jellies
relativley small and recently separated from cnidaria
-all marine, about 150 species
-8 rows of combs (ctenes) radially around body
-colloblasts- adhesive cells used in prey capture
-radial symmetry complete gut
-extracellular digestion in pharynx
-nerve net
-diploblastic
-mesoglea
Phylum Platyhelmenthes
-flatworms
-have epidermis
-turberellians (free living) lack cilliated covering
-avoids immune response from the host
-aceolomate body (parenchyma filled)
-incomplete gut (1 opening)
-mouth, pharynx, and intestine
-undigested food is egested through pharynx
-excretion: protonephrida (similar to kidneys), for excretion and osmoregulation
-contain flame cells to aid in movement
-beating flagella drivefluid through collecting ducts and outside pores
-have nerve cores
-subepidermal plexus (resebles cnidaria nerve net)
-bilobed ganglionic cells but no brain
-ocelli= light sensitive eyespots
-lack respritory, circulatory, and skeletal systems
-reproduce sexually (hermaphrodites but cross fertilize) and asexually (fission)
Class Turbellaria
-mostly free living
-5mm-50cm long
-simple gut or no gut
-can swim using cillia
-rythmical muscular waves pass backwards from head
Class Trematoda
-all parisitic flukes
-adults are endoparisites of vertabrates
-adaptations for parasitisim: penetration glands, glands to produce cyst material (forms flesh cave around fluke), hooks and suckers for adhesion, increased reproductive capacity,poorly developed sense organs
Class Cestoda
-tapeworms
-scolex-attaches to host(suckers and hooks)
-proglottids- inner series of reproductive units
-lack digestive system and sensory organs
-covered with microvilli which increase surface are for food absorption
Phylum Rotifera
-rotifers
-cillia around mouth appears like a rotating wheel
-diverse in color, shape, and size
-some are colonial
-water quality indicators and and improtand food source in aquatic ecosystems
-psuedoceolomate
-body has head, trunk, and tail
-beating of cillia helps with feeding and locomotion
-complete gut
-bilobed brain and nerves to run organs
-dioecious (males smaller than females)
-can withstand serious conditions
Phylum Acanthocephala
-spiny headed worms are intestinal parisites of vertebrates
-lack gut and jaws
-proposeis has recuved spines that penetrate intestines
-larve develop in crustacens or insects
-spiny probscus
Phylum Mesozoa
-considered "missing link"between protozoa and metazoa
-small, cilliated, wormlike
-are al parisites of marine invertebrates
-composed of only 20-30 cells in 2 layers
-live in kidneys of cephalapods
-larve are shed into seawater
-EX: rohmbozoans
Phylum Ectoprocta (Bryozoans)
-about 4500 species
-may encrust hard surfaces (including icebergs)
-mostly colony builders
-individual is less than 5mm in size
-werid blobby things, can be mistaken for salamander eggs
Phylum Brachiopoda
-lamp shells
-genus lingula
-considered a living fossil
-unchanged since the ordovician period (more than 400 mya)
-shells range in size from 5-80mm
-look like bivalves (clams)
Phylum Nemertea
-ribbon worms that are thread or ribbon shaped
-about 100 species
-have a long proboscis used to grab prey
-most are bigger than 20 cm long but some get to several meters
-nearly all marine
-some brightly colored, others are dull
-proboscis is unique to nemertens
-excretory system has flame cells
-mostly dioecious with cilliated larve
-adult has complete gut
-simplest animals with a closed loop blood-vascular system
-active predators (proboscis)
-some scavangers