WHOTeacher/Parent Helpers/7&8th grade helpers
MATERIALSSkates and Rays by Bobbie Kalman
Materials to make rays:
Traced rays on poster board, iridescent paint, googly eyes, scissors, white glue, paper clips and yarn.
WHAT1. Read book aloud to students, discuss and check for comprehension by making notes on chart paper OR watch video about rays: Skates and Rays
2. Review the physical characteristics of rays by labeling a large ray on chart paper.
3. Demonstrate how to cut and assemble their ray and how they can make it move like a real ray.
a. Students cut out the shape of the ray
b. Draw and label the parts of the ray
c. Attach the yarn for hanging with a rubberband
4. Students make models
5. As they finish they can go outside and have them practice making them swim like a ray.
6. Also can complete pages from their booklet about rays.
Support for differentiation: Use visuals and diagrams in book to support understanding of concepts.
Modification for different grade levels:
LS1.A Structure and function
LS1.B Growth and development of organisms
LS3.A Inheritance of Traits
LS4.B Natural Selection
Additional Background information needed:-A skate is a type of ray.
-Rays and sharks belong to the same family - ELASMOBRANCH.
-Rays descended from sharks and share many characteristics and have been around for more that 150 million years.
-A rays senses and reproductive methods are nearly identical to the shark’s/
-Skin, skeleton, organs and other body parts are like the shark’s.
-A rays flat body shape is the biggest difference between the sharks and rays.
-There are 500 species of rays. The skate is a type of ray, there are 200 species of skates.
-Rays are common in the world, they live in every ocean and sea, and a few live in rivers and lakes.
-Different rays prefer different water temps. Skates seem to like cooler waters in the waters far north or south of the equator.
-Most rays live in waters less that 200 ft deep. Skates choose deeper waters - up to 10,000 ft deep.
-Some ray species, including the manta ray, spend most of their lives in the open ocean. They sometimes come close to land, but don’t stay long.
-Rays have flat bodies called discs. The edges can wiggle or flap like wings. These “wings” are actually large pectoral, or side fins. The tail sticks out the back.
-Most ray’s skin is very smooth. Some have rough skin. Their bodies are covered with tiny teeth called dermal denticles-it protects them from injury. They are also covered with a slimy substance that helps it glide through the water.
-Rays have special skeletons that make them very flexible. They have cartilage instead of bone which is rubbery, strong and tough. This also makes it a good swimmer.
-Rays also have gill slits on the undersides of their bodies. They breathe by sucking in water through two holes called spiracles found on the top of its body. The water passes to internal gills. They take the oxygen out and squirt out the used water through the gill slits.
-Ray species can differ in many ways: size, from tiny to enormous. The smallest is called the shortnose electric, which is only 4 inches accross, and the manta ray which can be more than 22 ft across and weigh several tons.
-They can be round, triangular or wedge-shaped. The head may be completely built into the disc, or it may stick out in front.
-They can be all gray, all brown, or black with white spots, some are white and some are dotted with bright blue spots.
-They are graceful swimmers. They use their bodies/fins like wings, some can swim fast enough to jump out of the water.
-They must swim to stay afloat (unlike other fish who have an air-filled sac inside their bodies) they don’t get tired because they glide for long distances.
Sight - eyes on top of their bodies, use mostly for predators, excellent.
Smell - draw water through 2 nostrils near their mouths
Touch -
Electrical Senses -
Ampullae of Lorenzini - read faint electrical signals created by every living thing
Motion - Can sense at a distance
-Their mouth is on the underside of their body, they have many teeth-some have pointy, some flat depending on their diet.
-Rays are predators - they eat mostly fish, worms, shrimps, crabs, krill, clams, oysters and snails.
-They get their food from the bottom of the ocean. Some dig with snouts, some hide and sneak up.
-Manta Ray eat plankton.
-They have a poisonous barb at the end of their tail. Use it to jab predators.
-Sharks are their predators
-Electric Ray defends itself with electric shocks-up to 220 volts-can know a person off its feet.
-Use camouflage and countershading for defense also
-Skates lay eggs - are oviparous 6-12 months to develop depending on water temperature.
-Rays are ovoviparous - Eggs develop inside and young are born alive.