Lecture 14 Animal Kingdom Flashcards
Different domains
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Three domains
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Key characteristics of Eukaryotes (that distinguish from porkaryotes)
- eukaryotic group is very diverse,
- three main characteristics distinguishing them from prokaryotes:
1. Compartmentalization
2. Multicellularity in many, but not all, eukaryotes
3. Sexual reproduction
LEARNING OUTCOMES
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General Features of Animals
- Nutritional Mode
– Heterotrophy - obtain energy/ organic molecules by ingestion of food
– animals ingest food and then digest it internally - Cell Structure and Specialization
– Multicellularity - Many have complex bodies
– Tissues - organized into structural and functional units
– No cell walls – NO rigid cell walls and are usually flexible - Active movement - Move more rapidly and in more complex ways
- Diversity of form - Vary greatly in form, ranging in size from organisms too small to see with the unaided eye to enormous
- Reproduction and Development
– Sexual reproduction - Animal eggs, which are nonmobile.
– Embryonic development - Zygote, cleavage, blastula, gastrula - Larval stage possible with metamorphosis
Key Evolutionary Innovations of Animals
Five key transitions can be noted in animal evolution
– Tissues
– Symmetry
– Body cavity
– Patterns of Development
– Segmentation
Evolution of symmetry
There are two main types of symmetry:
Radial symmetry
– Body parts arranged around central axis
– Can be bisected into two equal halves in any 2-D plane
Bilateral symmetry
– Body has right and left halves that are mirror images
– Only the sagittal plane bisects the animal into two equal halves
Advantages
1. Cephalization - Evolution of a definite brain area
2. Greater mobility
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Evolution of tissues
Diploblastic - animals (cnidarians), have only ectoderm and endoderm
Triploblastic - animals, all bilaterally symmetrical animals produce three germ layers (Eumetazoa)
– Outer ectoderm (body coverings and nervous system)
– Middle mesoderm (skeleton and muscles)
– Inner endoderm (digestive organs and intestine
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3 germ layers
Ectoderm-forms the exoskeleton
Mesoderm-develops into organs
Endoderm- forms the inner lining of organs
Evolution of body cavities
Body cavity = Space surrounded by
mesoderm tissue that is
– Acoelomates = No body cavity
– Pseudocoelomates = cavity between
mesoderm and endoderm
Called the pseudocoelom
– Coelomates = Body cavity entirely within
the mesoderm
Called the coelom
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Bilaterians can be divided into two groups:
- Protostomes - develop mouth
first from or near the
blastopore
– Anus (if present) develops
either from blastopore or
another region of embryo - Deuterostomes - develop
the anus first from the
blastopore
– Mouth develops later from
another region of the
embryo
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Deuterostomes vs. protostomes
- Cleavage pattern of embryonic cells
–Protostomes = Spiral cleavage
–Deuterostomes = Radial cleavage - Developmental fate of cells
–Protostomes = Determinate development
–Deuterostomes = Indeterminate development - Formation of the coelom
–Protostomes = cells split off
–Deuterostomes = cells pouch off
Evolution of segmentation
Two advantages
1. Redundant organ system in adults
such as occurs in the annelids
2. Efficient and flexible movement
-segments can move independently
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Animal Phylogeny and diversification
Several data sources are used to infer evolutionary relationships among the three dozen extant animal phyla
–Whole genomes
–Morphological traits
–Ribosomal RNA (rRNA) genes
–Hox genes
–Protein-coding nuclear genes
–Mitochondrial genes
Animal Phylogeny and diversification
Five important points about the relationships among living animals are reflected in their phylogeny
- All animals share a common ancestor
- Sponges are the sister group to all other animals
- Eumetazoa is a clade of animals with tissues
- All animals except for sponges and a few others
belong to the eumetazoans (“true animals”) - Most animal phyla belong to the clade Bilateria
- There are three major clades of bilaterian animals
– Most bilaterians are invertebrates, animals that lack a backbone
– Chordata is the only phylum that also includes vertebrates, animals
with a backbone
Animal Phylogeny and diversification
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Summary of key concepts: key steps in animal evolution
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INVERTEBRATES
Classifying invertebrate species into groups based on evolutionary relationships helps us to understand their great diversity
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- Basis of the classification of animals
- Level of organization - multicellular
2.Type of symmetry – distribution around the main central axis
* Bilateral –median plane
* Radial – radiate from central axis
* Asymmetrical – no symmetry
3.Type of skeleton
* Endoskeleton –internal (bone or cartilage)
* Exoskeleton – external (calcium carbonate shells, chitin, silica)
- Nature of digestive tract
* Absent
* Incomplete – one opening (mouth for input and output)
* Complete – two openings (mouth and anus)
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Protosomes
- Phylum Porifera
- Phylum Cnidaria
- Phylum Ctenophora
- Phylum Platyhelminthes
- Phylum Mollusca
- Phylum Annelida
- Phylum Nematoda
- Phylum Arthropoda
Summary of key concepts: key steps in animal evolution
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Phylum Porifera
- Sponges
- Asymmetry
- Endoskeleton with spicules
- Various growth forms
– Larval sponges free-swimming
– Adults remain attached – sessile - Cell types
– Truly multicellular
– 3 functional layers in “vase” - Stationary
- Asexual or sexual reproduction
- Choanocytes
– Flagellated – contributes to water circulation
– Engulf and digest food from passing water
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Summary of key concepts: key steps in animal evolution
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Phylum Cnidaria
- radially symmetrical, diploblastic
- Carnivores - Tentacles for stinging prey, and defense
– First muscles and nerves - Extracellular digestion – one opening
– Digestion takes place partly in gastrovascular cavity
– Cells then engulf fragments by phagocytosis - Two body forms possible
– Medusae- free-floating “jelly-fish”
– Polyps- attached,
corals, sea anemones, Hydra
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Phylum Ctenophora
- Diploblastic, radial symmetry
- Resemble Cnidarian with their gelatinous, medusa-like form
- eight “combs” of cilia to propel them through water
- Comb jelly
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Summary of key concepts: key steps in animal evolution
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Phylum Platyhelminthes
- Most prominent group is the flatworms
– NO circulatory,
– NO respiratory systems - Diffusion for gas transport
– NO digestive system - absorb food directly through body walls – one opening
– planarians and parasitic flukes and tapeworms - Simple Bilateral symmetry, no coelom
- No coelom, Flatworms are ciliated, soft-bodied animals
- Parasitic or free-living - Marine, freshwater, moist terrestrial
- Cephalization - sensory equipment in the head
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Phylum Mollusca
- Second in diversity only to arthropods
- Soft bodied unsegmented animals
- Bilateral symmetry
- Exoskeleton - Protected by shells
- Include snails, slugs, clams, octopuses and others
- Reproduction - gonochoric
– A few are hermaphroditic
– Asexual reproduction - Major Classes
– Class Gastropoda – snails
– Class Cephalopoda –squids
– Class Bivalvia –clams
– Class Polyplacophora -chitons
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Phylum Annelida
- Segmented worms – earthworm, sandworm
– Body built of repeated units - Allows for specialization
– Head has well-developed cerebral ganglion - Bilateral symmetry
- Move by contracting their segments (filled with fluid)
– Longitudinal and circular muscles - Closed circulatory system
- Ventral nerve cord
- Complete digestive tract (two openings)
– Tube within a tube - Active burrowing affects climate change
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Summary of key concepts: key steps in animal evolution
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Phylum Nematoda
- Vinegar eels, eelworms, and other roundworms
- Found everywhere – abundant and diverse
- Marine, freshwater, parasites, free-living
- Bilaterally symmetrical and unsegmented
- Covered by a flexible, thick cuticle that is molted as they grow
- Digestive system well developed
– Stylets – piercing organs near mouth
– Pharynx – creates sucking action
– Anus - Sexual life cycle
- C. elegans - model organism
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Nematode-caused diseases
- Trichonosis, Trichinella
– Rare in U.S.
– Eating undercooked pork or bear
transmits the worms - Pinworms, Enterobius vermicularis
– Infects 30% of children in U.S.
– Causes itching of the anus - Serious tropical nematode disease
– Filariasis
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Phylum Arthropoda
- By far the most successful animals
– The most species (80% of all arthropods are insects) - Segmented body enclosed in exoskeleton of chitin
- First to live in air
- Bilateral symmetry/segmentation
- Jointed appendages on either side of the body
- Complete digestive tract (two openings)
- Divided into four extant classes (some books use subphylum)
– Chelicerata – spiders, mites, scorpions
– Crustacea – lobster, crabs, shrimps
– Hexapoda - insects
– Myriapoda – centi- millipedes
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Summary of key concepts: key steps in animal evolution
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Deuterostomes
- Deuterostomes are composed of echinoderms and chordates
- Consist of fewer phyla and species than protostomes
- Are more uniform in many ways, despite great differences in
appearance
❖ Phylum Echinodermata
❖ Phylum Chordata
Phylum Echinodermata
Exclusively marine (ocean)
* Deuterostomes with an endoskeleton
* Pentaradial symmetry
* Complete digestive tract (2 openings)
- Sea stars
- brittle stars,
- sea urchins,
- sand dollars,
- sea cucumbers
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Features of echinoderms
- Symmetry
– Pentaradial as adult, bilateral as larva
– Oral surface defines mouth
– All systems organized with branches radiating from center
– Nervous system is nerve ring with branches - Endoskeleton
– Epidermis covers endoskeleton
– Composed of calcium carbonate ossicles
– May be tightly or loosely joined - Water-vascular system - network of hydraulic canals branching
into extensions called tube feet (locomotion and feeding)
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Phylum Chordata (vertebrates)
- Chordates are deuterostome coelomates
- Most advanced animal group (more DNA)
- Nearest relatives are echinoderms (the only other deuterostomes)
- Four Characteristics of chordates
1. Nerve cord - develops in CNS
2. Notochord - May be replaced by vertebral column
3. Pharyngeal slits - gas exchange, feeding structures
4. Postanal tail - propelling force in many aquatic species
- Fishes
- amphibians
- reptiles
- birds
- mammals
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Phylum Chordata
- Chordates are deuterostome coelomates
- Nonvertebrate forms – subphyla urochordata, cephalochordata
– Do not form bone - Vertebrate forms
– Fishes, amphibians, reptiles, birds, and mammals
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Phylogeny of living Chordates
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KEY Characteristics of vertebrate evolution
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Non Vertebrates
A. Urochordata
* Tunicates are marine animals
* Larvae are tadpole-like and have notochord and nerve cord
– Are free-swimming but do not feed
* Adults typically lose the tail and notochord
– Are immobile filter-feeders
– Many secrete a tunic (cellulose sac) that surrounds the animal
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Non Vertebrates pt 2
B. Cephalochordata
- Lancelets are scaleless chordates
- Notochord persists throughout animal’s life
- Spend most of their time partly buried
- Have no distinguishable head
- Feed on plankton using cilia-generated currents
- Closest relatives to vertebrates
Vertebrata
- Chordates with a spinal column - Almost all chordates are vertebrates
- Distinguished from nonvertebrates by
– Vertebral column – Encloses and protects the dorsal nerve cord
– Head – Distinct and well-differentiated possessing sensory organs - Neural crest – unique group of embryonic cells that forms
many vertebrate structures (teeth, neurons, some bones) - Internal organs – liver, kidneys, endocrine glands, heart, and
closed circulatory system - Endoskeleton – made of cartilage or bone
– Makes great size possible and extraordinary powers of movement
- Fishes - Earliest and most diverse vertebrate group
- Over half of all vertebrates
- Provided the evolutionary base for invasion of land by amphibians
Characteristics - Vertebral column
– Hagfish and lamprey exceptions - Jaws and paired appendages
– Hagfish and lamprey exceptions - Internal gills
- Single-loop blood circulation
- Nutritional deficiencies
– Inability has been inherited by all their vertebrate descendants
Evolution of the jaw – Lampreys
- The first fishes had mouths with no jaws -jawless vertebrates
– Agnatha extant as hagfish and lampreys - Evolved from the anterior gill arches that were made of cartilage
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Lateral line development - Sharks
- Chondrichthyes – sharks and bony fish
- Cartilage skeleton “calcified” with granules of calcium carbonate -
Light, strong skeleton – sharks, skates, rays - Sharks - first vertebrates to develop teeth
- Sharks (and bony fishes) - fully developed lateral line system
– Series of sensory organs under the skin that detects changes in pressure waves
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The Swim bladder - Bony fishes
- Heavy internal skeleton made completely of bone
- New adaptations include: – Swim bladder - Gas-filled sac
regulate their buoyant density
– Gill cover - Hard plate (operculum)
covers gills Flexing plate permits water pumping over gilTwo groups of bony fish: - Ray-finned fishes
- Lobe-finned fishes
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- Amphibians - First Terrestrial Vertebrates
Evolutionary path to land
2. Amphibians - First Terrestrial Vertebrates
* Tetrapods:First vertebrates to walk on land * Direct descendants of fishes
* Amphibians evolved from lobe-finned fish
* 3 Modern Amphibian groups
– Order Anura (“without tail”) - frogs and toads
– Order Caudata (“visible tail”) - salamanders
– Order Apoda (“without legs”) - caecilians
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Five distinguishing amphibian features
- Legs – adaptation to life on land
- Lungs - Ribs
- Cutaneous respiration – supplement lungs
- Pulmonary veins – separate pulmonary circuit allows higher pressure blood to tissues
- Partially divided heart – improves separation of pulmonary and
systemic circuits
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- Reptiles - Adapted to Terrestrial Living
- Over 7,000 living species
Four key features
– Amniotic eggs, which are watertight, laid on land
– Dry skin, which covers body and prevents water loss
– Thoracic breathing, which increases lung capacity
– Ectothermy, they obtain heat from external sources
4.Birds - Flying Reptiles
Bird characteristics
* Class Aves
* Birds are the most diverse of all terrestrial vertebrates
* Success lies in unique structure – feather
* Amniotic eggs and scales on legs
* No teeth and no tails
* Two major distinguishing traits
– Feathers
– Flight skeleton
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Adaptations for flight
Adaptations birds have to cope with the energetic demands of flight
* Efficient respiration
– Air passes all the way through lungs in a single direction
* Efficient circulation
– 4-chambered heart so muscles receive fully oxygenated blood
– Rapid heartbeat
* Endothermy
– Body temperature (40–42oC) permits higher metabolic rate
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- Class Mammalia
- Lowest number among 5 vertebrate classes
A. Mammalian traits - Hair - Insulation, camouflage, sensory structure
- Mammary glands - secrete milk
- Endothermy depends on higher metabolic rate
– 4-chambered heart
– Respiration using diaphragm - Placenta (most mammals) - brings fetal and maternal blood into close contact
- Special adaptations in some groups
– Specialized teeth - match particular eating habits (carnivore vs herbivore)
– Digestion of plants - break down cellulose - Herbivorous mammals rely on mutualistic partnerships with bacteria
– Development of hooves and horns - Flying mammals: Bats
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- Evolution of Primates
- Gave rise to humans
- Evolved two features - success in an arboreal environment
– Grasping fingers and toes - Opposable thumb
– Binocular vision - Eyes shifted toward the front of the face - Lets brain judge distances precisely
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