This document summarizes the biology of sharks and rays. It discusses their internal organs like the liver, which is rich in oil and provides buoyancy for sharks. It also covers their reproductive modes, which can include oviparity where eggs are laid and hatch outside the body, viviparity where live young are born, and ovoviviparity where eggs hatch inside the uterus. The document examines shark and ray reproductive organs like claspers and cloaca, as well as mating behaviors. Examples of different shark and ray species are provided for each type of reproductive mode and internal anatomy.

1. Biology of
sharks and
rays

2. Liver
Internal organs of Mustelus lenticulatus
Spiral intestine

4. Liver (deep water shark: rich with oil)

6. Reproductive modes of shark
1. Oviparous:
Producing eggs that hatch after being ejected from the body of female parent
2. Viviparous
Producing live young from within the body of the parent female
Ovoviviporous
:Producing eggs that hatch inside the uterus then give birth to the young (whale shark)
1.
Shark Bony fish
Internal fertilization

8. What is this?

9. Scar on female body (love bite before
mating)

10. Mating bite

11. Mating scar

12. Internal fertilization
clasper
cloaca
Clasper
(modified portions of the
pelvic fins in male
sharks, rays and
chimaeras used for
transferring sperm to
the female
Cloaca
(a common opening for digestive,
urinary, and reproductive tracts in
many fishes)

13. Claspers
Mode of Reproduction

17. Viviparity (Live-bearing sharks)
Pregnant female of Centrophorus

20. Bull shark

23. Carcharhinus sealei
(2 pups)

25. Hemigaleus microstoma
(Weasel shark)

27. Whale shark; 350 pups

43. Oviparous

44. Egg cases of oviparous shark
Photo credit :
Dr. Keiichi Sato
Okinawa Churaumi Aquarium, Japan
Swellshark
Zebra shark
bambooshark

48. The egg case generally has tendrils and sticky
filaments that aide in attaching the egg to some
sort of substrate where the eggs incubate.

56. Smoothnose wedgefish.
Mode of Reproduction (Rays)
Viviparous: Producing live young from within the body of the
parent female

57. Pastinachus solocirostris

58. Neotygon kuhlii

59. Gymnura japonica
5 youngs

61. Rhina encylostoma

62. • Liver: Sharks have large livers that are
particularly rich in oil. It is thought that this oil
provides the animals with buoyancy, and helps
to prevent them from sinking when they are
stationary. Sharks which do not have air
bladders are heavier than water.
• Air bladder. Many bony fishes have air bladder
in their body cavity. By adjusting the amount
of gas it contains they are able to make their
bodies weightless in the water.
Other Information:

63. Liver
Carcharhinus lucas

64. Heart (very small compare with TL)

67. • Intestines: Sharks have short, compact
intestines which take the basic form of a spiral
staircase arrange within a cylinder. This spiral
valve-as it is known-varies in form from
species to species
• Bony fishes intestines vary in length according
to the type of food that is eaten. Meat eaters
generally have short intestines, and plant
eaters long ones, sometimes elaborately
folded

68. Spiral valve: Alopias supersiliosus