Chordates I (Tunicates, lancelets, and fish) Flashcards
What are the characteristics of Phylum Chordata?
1) Notochord
2) Pharyngeal gill slits
3) Dorsal Hollow Nerve Cord
4) Post-anal tail
5) Endostyle
What kind of embryological developmental pattern does Phylum Chordata undergo?
Deuterostome
What period did Chordates originate? When did they undergo rapid diversification?
Originated during the Precambrian period and diversified during the Paleozoic.
Are chordate body plans constrained?
No, least constraint of body plan = amazing diversity
What two invertebrate subphyla are included in Phylum Chordata?
Cephalochordata and Urochordata
What is the Notochord?
Works a endoskeleton for early muscles
-lost or replaced in some
What is the Hollow dorsal nerve cord?
Controls muscles, including brain (CNS)
-lost or replaced in Urochordates
What is the Pharyngeal gill slits (pouches)?
- Open to outside
- Used for respiration and feeding
- Become other structures in vertebrates
What is the endostyle?
- Thyroid Gland in vertebrates
- generates mucus for feeding
What is the post anal tail?
Synapomorphic feature in Chordates
- Propulsion, often with fins
- Vestifial trait in humans (coccyx)
What are the defining features of Phylum Chordata, Subphylum Cephalochordata?
Lancelets or “amphioxus”
- All 5 chordate features present
- Segmental muscles called myomeres
- Filter-feeders by passing water over pharyngeal gill slits covered in mucus
What is the body plan of Phylum Chordata, Subphylum Cephalochordata?
Filter feed with mucus sheet on pharyngeal gill slits (not for respiration)
- H2O is sucked through oral cirri
- food caught is sent to gut for digestion
- Water exits through atriopore
Closed Blood Vascular System
- No heart - peristalsis of vessels
- No blood pigments or cells
How do Phylum Chordata, Subphylum Cephalochordata reproduce?
External Fertilization with Simple Gonads
-Gametes shed directly into atrium and out atriopore
What is significant about Phylum Chordata, Subphylum Urochordata?
Loss of adult chordate features
Greater adaptation toward filter-feeding
What are the classes of Phylum Chordata, Subphylum Urochordata?
Class Ascidiacea - Benthic sea squirts
Class Thaliacea - Pelagic (drifter-planktonic)
Class Appendicularia (larvacea) - pelagic
What are the characteristics of Phylum Chordata, Subphylum Urochordata, Class Ascidiacea?
- Solitary and Colonial.
- Tadpole larvae have all 5 Characteristics but adult only have 2 (endostyle and pharyngeal gill slits)
- Feed like Cephalochordates
- No respiratory/excretory organs b/c it takes in so much water it accomplishes this through diffusion
Why is Phylum Chordata, Subphylum Urochordata, Class Ascidiacea important to humans?
They make unusual secondary metabolites so they are used in marine pharmocology
What are the characteristics of Phylum Chordata, Subphylum Urochordata, Class Thaliacea?
- Solitary and Colonial
- Take to open ocean by drifting (planktonic)
What are the characteristics of Phylum Chordata, Subphylum Urochordata, Class Appendicularia?
Pelagic and retain all 5 chordate features
- Makes up to 16 mucus houses per day (external struc)
- Abandoned houses source of “marine snow”
- Developing eggs fatally rupture body
What is significant about the mucus houses that What are the characteristics of Phylum Chordata, Subphylum Urochordata, Class Appendicularia make?
They are carbon sponges that draw carbon out of atmosphere and soak it up
What are the characteristics of Phylum Chordata, Subphylum Vertebrata=Craniata?
- Vertebral Column
- Cranium
- Endoskeleton
- Neural Crest
What is the vertebral column in Phylum Chordata, Subphylum Vertebrata=Craniata?
notochord is replaced by column of interlocking vertebrae
What is the cranium in Phylum Chordata, Subphylum Vertebrata=Craniata?
Protective housing around brain
What is the endoskeleton of Phylum Chordata, Subphylum Vertebrata=Craniata?
Grows with body; First cartilage then bone
What is the neural crest of Phylum Chordata, Subphylum Vertebrata=Craniata?
Embryonic cells, contribute to development of the cranium
What are the five extant classes of the paraphyletic group of fish in Phylum Chordata, Subphylum Vertebrata=Craniata?
1) Myxini - hagfishes
2) Petromyzontida - lampreys
3) Chondrichthyes - sharks, skates, rays
4) Actinopterygii - ray-finned fishes
5) Sarcopterygii - lobe-finned fishes
What is the evolutionary progression of the endoskeleton in fishes?
Notochord to vertebral column
-cartilage to bone
What is the evolutionary progression of the Pharynx in fishes?
Pharyngeal gill slits to gills
-greater respiratory capacity
What is the evolutionary progression of the Nervous System in fishes?
greater development of senses and brain
What is the evolutionary progression of the Appendages in fishes?
greater development of paired pectoral and pelvic fins
What is the evolutionary progression of the Jaws in fishes?
modified cartilaginous gill arches derived from neural crest cells with jaw muscles from gills
How did gill arches in primitive jawless fish evolve in early jawed fishes to result in modern jawed fish?
From 9 gill arches in primitive jawless fish to
Gill arches 1 and 2 lost and gill arch 3 modified to form hinged jaw in earlier extinct jawed fishes
Gill arch 4 modified to form heavier more efficient jaw in modern jawed fishes
What are the characteristics of the Phylum Chordata, Subphylum Vertebrata, Class Myxini (hagfish)?
Lack JAWS, scales, paired fins, bone
Scavengers
Keratin teeth on tongue used for rasping food
Slime glands make sheet of mucus
What are the characteristics of the Phylum Chordata, Subphylum Vertebrata, Class Petromyzontida (lampreys)?
Lack JAWS, scales, paired fins, bone
Keratin teeth around sucker-like mouth may be used to parasatize
-not all are parasites
Life cycle involves ammocoetes larva that filter-feeds like cephalochordate but respire with gills
What are the characteristics of the Phylum Chordata, Subphylum Vertebrata, Class Chondrichthyes (sharks, skates, rays)?
Has JAWS, paired pelvic and pectoral FINS, PLACOID SCALES adapted to form teeth
Cartilaginous skeleton - lighter than bone to maintain position in water
Osmoregulation requires copulation and shelled eggs
No swim bladder, exposed gills, and heterocercal caudal fin
What are the characteristics of the Phylum Chordata, Subphylum Vertebrata, Class Actinopterygii (ray-finned fish)?
Has JAWS, paired pelvic and pectoral FINS, lightweight cycloid, ctenoid or ganoid scales
Bony skeleton, gills covered by bony operculum, and homocercal caudal fin
Swim bladder may be present
Osmoregulation permits free-spawning and planktonic development
What are the characteristics of the Phylum Chordata, Subphylum Vertebrata, Class Sarcopterygii (lobe-finned fish)?
Has JAWS, paired pelvic and pectoral fins, heavy enameled scales
Bony skeleton, gills covered by bony operculum, Diphycercal caudal fin
Swim bladder acts as a lung in lungfish
Strong, fleshy lobed-fins = lineage gave rise to tetrapod
All predatory
What fish is a ‘‘living fossil’’?
Coelocanth, a mesozoic relect
belongs to class sarcopterygii
