Chordates and Vertebrates The Agnatha – Jawless Fish.
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Chordates and Vertebrates
The Agnatha – Jawless Fish
HomeworkRead p 146- 147
1. How long ago did the first vertebrate fish appear in the oceans?
2. What are four basic characteristics of vertebrates?
3. What are the most primitive type of fish living today? Give an example.
4. How do hagfish feed?5. What Kingdom and class are bony fish
grouped in?
Phylum Chordata
• 4 Distinguishing characteristics– Hollow, dorsal nerve cord– Pharyngeal gill slits– Stiffening notochord– Post anal tail
– BODY ADVANCES– Dorsal Nerve Cord– Backbone or Notochord
Chordate Characteristics
The nerve cord is found on the ________ side of the organism
Ven
tral
Post
erio
r
Dors
al
Ante
rior
8%0%
92%
0%
1. Ventral
2. Posterior
3. Dorsal
4. Anterior
3 Subphyla of Chordates
• Urochordates – tunicates
• Cephalochordates – lancelets
• Vertebrates – fish, amphibians, reptiles, birds, mammals
Urochordates- Tunicates
AKA “Sea Squirts”
These are the ONLY sessile ChordatesFilter feeders which pump and filter water to feed tunicates have a larva that is free-swimming and exhibits all chordate characteristics :•a notochord, •a dorsal nerve cord, •pharyngeal slits,•post-anal tail.
Lancelet Laterally compressed filter feeders.
Cephalochordates
They Possess-Dorsal Nerve cord-Notocord- pharyngeal slits or "gill slits“ BUTCephalochordates lack features found in most or all true vertebrates: the brain is very small and poorly developed, sense organs are also poorly developed, and there are no true vertebrae
Subphylum Vertebrata
• Members have all the major characteristics of the phylum plus…
• have a vertebral column (backbone or spine)– made up of vertebra– protects nerve cord (spinal cord)
Sea Squirts are
Ben
thic
Infa
una
Ses
sile
Dem
ersa
l
23%
8%
62%
8%
1. Benthic
2. Infauna
3. Sessile
4. Demersal
5 classes of Vertebrates:
•Birds•Fish•Reptiles•Amphibians•Mammals
Vertebrates are built for an active lifestyle
• Bilateral symmetry
• Endoskeleton – axial and appendicular
• Extreme cephalization
• Complex organ systems
Organ systems are more complex because vertebrates are bigger, more active
• Respiratory – gills or lungs
• Circulatory – closed; 2,3 or 4 chambered heart (fish, reptiles, mammals respectively)
• Digestive – accessory organs for digestion of more varied diets
There are _____ classes of Vertebrates
3 5 4 2
15%
8%
23%
54%
1. 3
2. 5
3. 4
4. 2
2 big vertebrate groups
• Superclass Gnathostomata I– 3 classes of fish
• Superclass Gnathostomata II– All the tetrapods
• Amphibians• Reptiles• Birds• Mammals
3 fish classes
• Agnatha – jawless fishes
• Chondrichthyes – cartilaginous fishes
• Osteichthyes – bony fishes
Protochordate Overview
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