1. Chapter 30
Chordates

2. 30-1 Phylum Chordata Chordate Characteristics:
Notochord. All chordate embryos have a notochord, which is a longitudinal, flexible rod of cartilage located between the gut and the dorsal nerve cord. The notochord may persist into adulthood in some chordates, but in many it is replaced by the vertebral column. The spongy material (disks) in between the vertebral bones is all that is left of the notochord.

3. Dorsal Hollow Nerve Cord
Dorsal Hollow Nerve Cord. The nerve cord of a chordate embryo is formed from a plate of dorsal ectoderm that rolls up into a tube. It will develop into the chordate's central nervous system .
Pharyngeal Pouches/ Gill slits. These paired structures are openings of the upper digestive tube in chordates. The pharynx is the area just behind the mouth. As time progressed the slits became modified to function in gas exchange.

4. Post anal Tail. Most chordates have a tail extending beyond the anus
Post anal Tail. Most chordates have a tail extending beyond the anus. In many aquatic species the tail is equipped with skeletal and muscular tissue for movement.

5. Figure 30–1 The Generalized Structure of a chordate
Muscle segments
Tail
Anus
Pharyngeal pouches
Mouth
Hollow nerve cord
Notochord

6. Subphyla of Chordata: Subphylum Cephalochordata.
Lanclets- small fishlike creatures. Exhibit a closed circulatory system.
Subphylum Urochordata. The common organisms are called tunicates. The adults lose 3 of the chordate characteristics as adults: Notochord, nerve chord , and tail.
Subphylum Vertebrata. A vertebrate is any chordate that has a backbone.

7. Cephalization, development of highly specialized sensory structures and a highly specialized brain.
One end of the nerve cord becomes the brain.
Vertebral column, The axial skeleton (skull, ribs, and vertebra) and the appendicular skeleton (arms and legs, or wings, or flippers) is an internal living system.

8. Closed circulatory system. It is a closed system
Closed circulatory system. It is a closed system. The heart is composed of a collecting chamber(s)-atrium and a pumping chamber(s)-ventricle. The cells of the body exchange food and gases through tiny blood vessels called capillaries.
The kidney is the main excretory organ.

9. Sexes are separate. Fertilization may be internal or external depending on the species.
Respiratory organs include the gills, lungs, or highly vascularized skin. Oxygen is carried to all parts of the body in a liquid called blood. Hemoglobin is the main attractant of oxygen and is found in the red blood cells.

10. jawless, cartilage skeleton, gill slits, no swim bladder
Class
Main Characteristics
Examples
Agnatha
jawless, cartilage skeleton,
gill slits, no swim bladder
Lamprey and Hagfish
Chondrichthyes
Placoid scales,
cartilage skeleton
internal fertilization,
paired fins,
Sharks, Rays, and Skates
Osteichthyes
Bony skeleton, paired fins, operculum, swim bladder
Tuna, Bass, Catfish, Flounder
Amphibia
Smooth skin, no claws, aquatic larvae, breathe through lungs and skin
Frogs, Salamanders, and Toads

11. Class
Main Characteristics
Examples
Reptilia
Amniote egg, rough,dry skin, respiration through lungs
Snakes, Lizards, Turtles, and crocodiles
Aves
Feathers, amniote egg, extensive lung system, and wings
Birds
Mammalia
Hair, diaphragm, mammary glands, and bear live offspring.
Marsupials, monotremes, and Placentals

12. 30–2 Fishes Fish are aquatic vertebrates that are characterized by:
paired fins
scales
gills.

13. Evolution of Fishes (1st Vertebrates to evolve)
The evolution of jaws and paired fins:
Go from prey to predator
During the late Cambrian Period

14. Adaptations to aquatic life
Respiration
Most fishes exchange gases using gills located on either side of the pharynx.
Circulation
Fishes have closed circulatory systems with a heart that pumps blood around the body in a single loop.

15. Adaptations to aquatic life
Excretion
In the form of ammonia.
Wastes diffuse through the gills
Others are removed by kidneys
Circulation in a Fish
In most fishes, the heart consists of four parts:
the sinus venosus
atrium
ventricle
bulbus arteriosus

16. Circulation in a Fish Section 30-2 Gills Brain and head circulation
Sinus Venosus
Atrium
Oxygen-poor blood from the veins collects in the sinus venosus.
Blood enters the atrium and flows to the ventricle.
Body
muscle
circulation
Digestive
system
circulation
Heart
Ventricle
Bulbus Arteriosus
The ventricle pumps blood into the bulbus arteriosus.
The bulbus arteriosus moves blood into the ventral aorta and toward the gills.
Oxygen-rich blood
Oxygen-poor blood

17. Response Olfactory bulbs- which are involved with the sense of smell.
Cerebrum- is responsible for all voluntary activities of the body. However, in fishes, the cerebrum primarily processes the sense of smell.
Cerebellum-coordinates body movements.

18. Response
Medulla oblongata- controls the functioning of many internal organs.
Almost all fishes that are active in daylight have well-developed eyes and color vision that is at least as good as yours.
Lateral line system. Fishes use this system to sense the motion of other fishes or prey swimming nearby.
Swim bladder that adjusts their buoyancy.

20. Reproduction
Oviparous:Lays eggs, externally fertilized, as the embryos of oviparous fishes develop, they obtain food from the yolk in the egg.

21. Reproduction
Ovoviviparous, the eggs stay inside the mother’s body after internal fertilization. Each embryo develops inside its egg, using the yolk for nourishment. The young are then “born alive”.

22. Reproduction
Viviparous- the embryos stay in the mother’s body, as they do in ovoviviparous species. However, these embryos obtain the substances they need directly from the mother’s body. The young of viviparous species are also born alive.

23. Class Agnatha: Jawless Fish
(Lamprey and Hagfish)
General Characteristics:
Absence of jaws.

24. These organisms lack paired fins (pelvic and pectoral).
Class Agnatha:
These organisms lack paired fins (pelvic and pectoral).
Skeleton made of cartilage.
Round eel-like body with a compressed caudal fin.
Soft skin devoid of scales.

25. Class Agnatha:
They lack a swim bladder and gill covers (operculum).
The lamprey are parasitic and the hagfish are scavengers.
Ectothermic ( animals that cannot control their body temperature).

26. External fertilization. Oviparous ( egg laying) Lateral line
Class Agnatha:
External fertilization. Oviparous ( egg laying)
Lateral line
Two chambered heart
Gills used for respiration (gas exchange)

27. Class Chondrichthyes: Chondrus=Cartilage
( Sharks, Rays, and Skates).
General Characteristics:
Skeleton made of cartilage.
Body covered with triangular Placoid scales.

28. Class Chondrichthyes:
Large caudal fin with the dorsal section larger than the ventral one.
Paired fins ( pectoral and pelvic), are stiff and nonflexible.
They lack a swim bladder.

29. Class Chondrichthyes:
Ectothermic
Internal fertilization.
Ovoviviparous ( developing egg kept inside the female for protection and does not live off of the parent).
Marine organisms only.
Lateral line

30. Class Chondrichthyes:
Two chambered heart
Gills used for respiration
No external ears
No eye lids

31. Class Osteichthyes: Boney Fish
( Tuna, Carp, Salmon, and Sturgeons).
General Characteristics:
Skeleton made of bone
Lateral line
Two chambered heart
Operculum covering the gills.
Swim bladder

32. Class Osteichthyes:
Ectothermic
Paired fins made of rays and spines, or lobed fins lacking the rays and spines.
Various types of scales
Marine and fresh water species.

33. Class Osteichthyes:
Gills used for respiration
External fertilization. Spawning. Oviparous.
No external ears
No eye lids.