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Chordates and Fish
What is a chordate?
Members of the
KINGDOM ANIMALIA
and the PHYLUM CHORDATA
They have a dorsal, hollow nerve cord
and a notocord
Chordates have
●pharyngeal pouches (become gills)
●Tail - extends beyond anus
Most chordates are vertebrates
(SUBPHYLUM VERTEBRATA)
Chordates that are NOT vertebrates:
Sea Squirts or Tunicates
Lancelet
Chordate Anatomy
Consider this....
All vertebrates are chordates.................
But not all chordates are vertebrates.NO WAY!!!!
What is a vertebrate?
-Animals with a backbone (and endoskeleton)
-Have spinal cord (dorsal, hollow nerve cord)
-Front end of spinal cord develops a brain
Quick Check
1. Members of the Phylum __________ have a dorsal hollow nerve cord.
2. During development, the pharyngeal pouches will become ___________
3. All chordates belong to the animal kingdom. (T or F )4. All chordates are vertebrates. (T or F )5. You are more closely related to a sea squirt than to an earthworm.
5. What are two animals that are chordates, but not vertebrates?
6. An animal with a backbone is called a _________.
Vertebrate Classes
●Jawless Fish (lamprey, hagfish)
●Cartilage Fish (sharks, rays…)
●Bony Fish (salmon, catfish, goldfish…)
●Amphibians (frogs, salamanders…)
●Reptiles (lizards, turtles…)
●Birds (sparrows, hawks…)
●Mammals (humans, whales, cats..)
What are Fish?* Anything with gills, scales, and fins…
●1st Fish were jawless
●Devonian Period - "Age of Fishes“
Fossil of a devonian fish with
jaws and armored plates
Stethacanthus Tribute Video
Form & Function
1. Circulation
Fish have a two chambered heart –
blood is passed over the gills where it
picks up oxygen
2. Respiration●Water passes over GILLS, oxygen is added
●Some fish have gill covers – OPERCULUM
●Some fish have special organs to serve as
lungs (Lungfish)
3. Excretion●Homeostasis: maintaining water
balance
●Salt water fish tend to lose water
●Freshwater fish tend to gain water
*This is why you can’t put a salt water fish in a
fresh water tank
*The salmon can do both
4. The Nervous System
Response
- Cerebrum - thinking, voluntary activities
- Cerebellum - coordination
- Medulla Oblongata - functions of internal
organs
- Lateral Line System - senses vibrations
Quick Check over Form and Function
1. Fish have _____________________ loop circulation. Mammals and birds have ____________________ loop circulation.
2. The two chambers of the fish heart are the _______________ and ______________
3. Blood leaves the heart goes to the gills and then to the ____________ before it returns to the heart.
4. The covering of the gills is the _________________________
5. __________________________ is the maintaining of a water balance.
6. The part of the brain used for thinking and learning is the ______________________
7. The part of the brain used for balancing is the ______________________
8. The _________________ ___________ system senses vibrations.
9. Early fish did not have _________________________. What fish alive today are like that? _________________ and _______________
Other Fish Adaptations
A. Swim Bladder –
maintains buoyancy (like a balloon)
Sharks do not have a swim bladder, if they stop swimming, they sink.
B. FINS
C. SCALES
Scales cover and protect the fishMucus on scales help fish swim The rings on a scale tell the fish’s age
5. Reproduction
Spawning – fish lay eggs that are fertilized
externally
Some fish bear live young
This 1 minute video shows a lemon shark give birth to live young.
Some sharks lay eggs.
Types of Reproduction●Oviparous (lays eggs)
●Ovoviviparous (eggs stay in mom)
●Viviparous (babies get nourishment from mom.
Ex. Humans, cats, some fish)
Salmon Video at National Geographic
