General Zoology Unit Five

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General Zoology Unit Five
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Hemichordata
Eukaryotic, eumetazoans, deuterostomes
Triploblastic, eucoelomates
Bilaterally symmetrical (cephalization)
Worm like body divided into three segments
Complete digestive system
Closed circulatory system with dorsal heart
Respiration through gill slits
Sexual reproduction dioecious, external
fertilizers with metamorphosis
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Phylum Hemichordata
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Chordate Characteristics
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Chordate Taxonomy
Kingdom - Animalia
Phylum - Chordata
Subphylum - Urochordata (tunicates)
Subphylum - Cephalochordata (lancelets)
Ex. Branchiostoma
Subphylum - Vertebrata
Superclass - Agnatha
Class - Myxini (hagfish)
Class - Cephalaspidomorphi (lampreys)
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Chordate Taxonomy
Kingdom - Animalia
Phylum - Chordata
Subphylum - Vertebrata
Superclass - Gnathostomata
Class - Chondrichthyes (sharks, skates, rays)
Class - Actinopterygii (ray finned bony fish)
Class - Sarcopterygii (lobe finned bony fish)
Class - Amphibia
Class - Reptilia
Class - Aves
Class - Mammalia
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Subphylum Urochordata
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Subphylum Urochordata
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Subphylum Cephalochordata
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Garstangs Hypothesis of Vertebrate Evolution
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Developmental Definitions
Paedomorphosis - the retention of larval traits
in the adult body
Neotony - a process in which the growth rate is
slowed to the extent that sexual maturity is
reached before the ancestral adult form is
obtained
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Developmental Definitions
Progenesis - the precocious maturation of the
gonads in a juvenile body that stops growing and
never attains the adult body form
Post-displacement - a delay of the onset of a
developmental process relative to sexual
maturity, so that the ancestral adult form is not
attained before reproductive maturity
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Garstangs Hypothesis of Vertebrate Evolution
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Vertebrate Ancestry
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Fish Taxonomy
Kingdom - Animalia
Phylum - Chordata
Subphylum - Vertebrata
Superclass - Agnatha
Class - Myxini (hagfish)
Ex. Myxine
Class - Cephalaspidomorphi (lampreys)
Ex. Petromyzon
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Fish Taxonomy
Kingdom - Animalia
Phylum - Chordata
Subphylum - Vertebrata
Superclass - Gnathostomata
Class - Chondrichthyes (sharks, skates, rays)
Subclass - Elasmobranchii (sharks, skates, rays)
Ex. Squalus, Raja
Subclass - Holocephali (chimeras or ratfish)
Ex. Chimera
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Fish Taxonomy
Kingdom - Animalia
Phylum - Chordata
Subphylum - Vertebrata
Superclass - Gnathostomata
Class - Actinopterygii (ray finned bony fish)
Ex. Perca, Amia, Polyodon
Class - Sarcopterygii (lobe finned bony fish
Ex. Latimeria
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Subphylum Vertebrata
All five chordate hallmark characteristics
Endoskeleton of cartilage or bone
Complete digestive tract
Closed circulatory system with a ventral heart
Complex nervous system with a brain, dorsal nerve
cord and advanced sense organs
Excretion carried out by paired kidneys
Most have two pairs of appendages
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Superclass Agnatha
All members have the vertebrate characteristics
All are jawless
All are elongated and eel shaped
None have paired appendages
Scales are absent
Complete digestive system without a stomach
The notochord is persistent into adulthood
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Superclass Agnatha
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Superclass Agnatha
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Superclass Gnathostomata
All members have the vertebrate characteristics
All members have a jaw
All have or have had paired appendages
All have an endoskeleton of cartilage or bone
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Class Chondrichthyes
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Class Chondrichthyes
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Class Chondrichthyes
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Class Chondrichthyes
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Class Actinopterygii
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Class Actinopterygii
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Class Actinopterygii
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Class Sarcopterygii
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Class Sarcopterygii
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Osmoregulation in Fish
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Respiration in Fish
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Respiration in Fish
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Respiration in Fish
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Vertebrate Thermoregulation
Ectothermic obtaining body heat from the
environment
Poikilothermic non-regulatory, the body
temperature is the same as the ambient environment
Regulatory ectotherms maintain a consistent
body temperature through physiological and
behavioral means
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Vertebrate Thermoregulation
Endothermic body heat is produced internally
(homeothermic)
Fish are poikilothermic because water is a heat
sink
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Buoyancy in Fish
Squalene (liver oil)
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Buoyancy in Fish
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Physostomous bladder
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Buoyancy in Fish
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Physoclistous bladder
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Fish Feeding Strategies
Most fish are carnivores
Most ocean species are suspension feeders
Some are scavengers
A few species are parasites
A few species are herbivores
A few species are omnivores
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Fish Reproductive Adaptations
Oviparous - egg laying
Ovoviviparous - retention of eggs
Viviparous live birth
All three methods are found in cartilaginous and
bony fishes
Cartilaginous fish are internal fertilizers while
most bony fish are external fertilizers
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Fish Reproductive Adaptations
Diadromous - fish that make two runs in their
life to live and reproduce
Anadromous - fish that run up - salmon
Catadromous - fish that run down - eels
Parthenogenesis - no males required, females
produce diploid eggs - Amazon molly
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Amphibian Taxonomy
Kingdom - Animalia
Phylum - Chordata
Subphylum - Vertebrata
Superclass - Gnathostomata
Class - Amphibia
Order - Gymnophiona (caecilians)
Order - Caudata (salamanders)
Ex. Ambystoma, Necturus
Order - Anura (frogs)
Ex. Rana, Bufo
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Class Amphibia
All five chordate hallmark characteristics
Endoskeleton of bone
Thin, gland rich skin with no scales or claws
Large mouth - all members carnivores
Closed double looped circulatory system with a
ventral three chambered heart
Respiration - lungs, gills or cutaneous
Regulatory ectotherms
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Class Amphibia
Excretion through opisthonephric kidneys and urea
as the primary nitrogenous waste
Nervous system with a brain and dorsal nerve cord
- well developed sight and hearing
Reproduction dioecious, some internal, others
external fertilizers, some metamorphosis
Most are tetrapods
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Order Gymnophiona
Caecilians
Legless, elongated worm-like bodies
Fossorial, tropical subtropical organisms
Most are blind, with smell and touch being the
best senses
Eggs are laid in moist soil
Some species are viviparous
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Order Caudata
Salamanders, newts, amphiumas, sirens
Most have four legs all have a tail
Some aquatic, some terrestrial
Respiration by gills, skin and lungs
Internal fertilization
Metamorphosis and direct development
Paedomorphosis common
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Order Anura
Frogs
All have four legs and no tail (one exception)
Some aquatic, some terrestrial
Respiration by skin and lungs
Good vision and nictitating membranes
External fertilization
Metamorphosis and direct development
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Amphibian Evolutionary Pressures
Respiration
Thermoregulation
Support
Ecological diversity
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Amphibian Respiratory Strategies
Cutaneous
Pulmonary
Buccopharyngeal
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Amphibian Respiratory Strategies
Gills
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Amphibian Circulation
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Amphibian Circulation
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Amphibian Thermoregulation
Many amphibians are regulatory ectotherms, using
physiological and behavioral means
Aquatic species and salamanders are
poikilothermic, but other terrestrial species
will drop to this level of thermoregulation
during hibernation and estivation
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Amphibian Metamorphosis
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Caudatan Development
Remember! Neotony - a process in which the growth
rate is slowed to the extent that sexual maturity
is reached before the ancestral adult form is
obtained
In caudatans there are two forms of neotony -
obligate and facultative
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Obligate neotony
Facultative neotony