Phylum Chordata the “chordates”Chordata CharacteristicsSlide 3Slide 4Slide 5Slide 6Slide 7Slide 8Phylum ChordataSubphylum Urochordata tunicates, ascidians, sea squirts, etc.Subphylum UrochordataSlide 12Slide 13Subphylum Cephalochordata the lancelets (amphioxus)Subphylum CephalochordataSubphylum Vertebrata the vertebratesSubphylum VertebrataSlide 18Slide 19Class Agnatha jawless fishClass AgnathaClass Chondrichthyes the sharks and raysClass ChondrichthyesSlide 24Slide 25Class Osteichthyes the “bony” fishClass OsteichthyesSlide 28Class Amphibia frogs, toads, and salamandersClass AmphibiaSlide 31Slide 32Slide 33The Amniotic EggClass Reptilia lizards, snakes, turtles, alligators, and crocodilesClass ReptiliaSlide 37Slide 38Class Aves birdsClass AvesSlide 41Slide 42Class Mammalia the mammalsClass MammaliaSlide 45Slide 46How does Chordata fit in?Phylum Chordata the “chordates”Chordata CharacteristicsTriploblasticCephalizationBilateral symmetryOrgan level of organizationEucoelomateDeuterostomeChordata CharacteristicsComplete digestive systemClosed circulatory systemEndoskeletonChordata CharacteristicsAll chordates possess these 4 unique characters at some point in their life (even if they disappear later on):• notochord• dorsal hollow nerve cord• pharyngeal slits• postanal tailbasic chordate body planmouthanusChordata CharacteristicsNotochord• a flexible rod-like structure• extends the length of the body • an axis for muscle attachment• in all jawed vertebrates, it is replaced by a series of cartilaginous or bony vertebraeChordata CharacteristicsDorsal hollow nerve cord• a single hollow tube-like nerve cord • dorsal to the alimentary canal and the notochord • in vertebrates, the anterior end becomes enlarged to form the brainbrainChordata CharacteristicsPharyngeal slits• perforated slit-like openings that connect the pharyngeal opening and the outside• formed by alternating pharyngeal grooves and pouches• in aquatic chordates, they become the gills • in tetrapod (4 limbed) vertebrates, they become parts of the throat and ear cavityChordata CharacteristicsPostanal tail• located posterior to the anus• associated with somatic musculature• provides motility in the aquatic environmentsegmented myotomes anchored to notochordPhylum ChordataSubphylum UrochordataSubphylum CephalochordataSubphylum VertebrataSubphylum Urochordatatunicates, ascidians, sea squirts, etc.Subphylum Urochordata• swimming “tadpole larva”possesses all 4 chordate characteristics• sessile adults have lost all chordate characteristics except pharyngeal gill slitsSubphylum UrochordataLarval Anatomynotochorddorsal nerve cordgill slitspharynxPostanal tailmouthanusSubphylum Urochordatagill slitspharynxmouthanusintestineAdult Anatomyexcurrent siphonincurrent siphonused for filtering foodSubphylum Cephalochordata the lancelets (amphioxus)Subphylum Cephalochordata• have all 4 chordate characteristics throughout the lifecyclegill slitsdorsal nerve cordnotochordpostanal tailSubphylum Vertebratathe vertebratesSubphylum Vertebrata• have an endoskeleton consisting of a vertebral column, and in most classes, limb girdles and paired appendagesaxial skeleton- consists of skull and vertebral columnappendicular skeleton- consists of paired limbsSubphylum Vertebrata• outer epidermis (skin) that is modified into specialized structures (e.g. hair, scales, feathers…)• ventral heart with 2- 4 chambers• hemoglobin filled blood cells• paired kidneys• highly differentiated brain• endocrine system with glands scattered throughout bodySubphylum VertebrataClass Agnatha*Class ChondrichthyesClass OsteichthyesClass AmphibiaClass ReptiliaClass AvesClass Mammalia* Note that in your textbook this is a superclassClass Agnathajawless fishClass Agnatha• jawless with a sucker-like oral disk containing well developed teeth• fibrous and cartilaginous skeleton with no vertebrae• no scales; no paired appendages• pore-like gill openings• two chambered heart• no stomach only intestineClass Chondrichthyesthe sharks and raysClass Chondrichthyes• cartilaginous skeleton with bony jaws• paired appendages• two chambered heart• heterocercal tail (asymmetrical)• exposed gill slits (no operculum)• no swim bladder• internal fertilizationgill slitsClass Chondrichthyes• skin is covered with dermal scales which are also modified to form teethClass Chondrichthyes• although many sharks are feared predators, some are harmless filter feedersClass Osteichthyesthe “bony” fishClass Osteichthyes• mostly bony skeleton• skin covered in dermal scales• paired appendages• two chambered heart• gills supported by bony gill arches and covered by an operculum• most have a homocercal tail (asymmetrical)• have a swim bladderClass Osteichthyes• some species of fish are sequential hermaphrodites they may change sex during their lifeClass Amphibiafrogs, toads, and salamandersClass Amphibia• mostly bony skeleton• 4 limbs (tetrapods)• smooth, moist, glandular skin• three chambered heart• gills, lungs, and/or skin respiration• ectothermic (body temperature matches the temperature of the environment)Class Amphibia• metamorphosis usually occurs from a gill breathing larva to a lung breathing adult• soft eggs tie amphibians to waterClass Amphibia• many amphibians have amazing parental behaviorSubphylum VertebrataClass AgnathaClass ChondrichthyesClass OsteichthyesClass AmphibiaClass ReptiliaClass AvesClass MammaliaAmniotesThe Amniotic Egg• the 3 remaining classes (reptiles, birds, and mammals) have amniotic eggs• amniotic eggs are shelled and contain a fluid-filled sac (the amnion) that surrounds the embryo• the evolution of the amniotic egg allowed the amniotes to reproduce away from waterClass Reptilializards, snakes, turtles, alligators, and crocodilesClass Reptilia• mostly bony skeleton• 4 limbs (tetrapods)• body covered by horny, epidermal scales • few glands• three chambered heart (except for crocodilians)• respiration exclusively by lungs• amniotic egg• ectothermicClass Reptilia• many reptiles have temperature dependent sex determination The incubation temperature of the nest determines the sex of the offspring• In crocodiles: • high temperatures produce males• low temperatures produce females• In turtles:• high temperatures produce females• low temperatures produce malesClass Reptilia• some snakes retain their
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