WAVE on Wheels Outreach
Ray Cart Presentation
Grades 6-8
Time requirement
1 Hour
Group size and grade
Up to 50 students maximum
Materials
2 Yellow Stingrays – in large transport cooler
1 or 2 water coolers (depending on the length of trip and need for a water change)
Mobile Shark Cart
Blue basket (including Pump, Ray Net, Electrical Cord, Paper towels)
Thermometer
Ray Artifacts Bin
Ray Emergency Water
WAVE Tablecloth
Goal
Through a live ray encounter, students will be excited, engaged, and educated about the
wonders of aquatic life and the importance of conservation.
Objectives
1.
Students will be able to list 3 adaptations a ray has for aquatic life including a
combination of internal and external body parts as well as behaviors.
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2.
3.
4.
5.
6.
Students will be able to list at least 3 animals closely related to sting rays and identify a
unique characteristic to that species.
Students will be able to discuss biological factors relating to ray population numbers,
individual growth rates, and reproductive success.
Students will be able to describe that all energy in a food web originated from the sun.
Students will be able to discuss ray conservation efforts as well as how they can help
save rays and other aquatic animals.
Students will be able to design and describe a method for monitoring and minimizing
human impacts on ray environments.
Theme
Stingrays are often misunderstood animals that play an important role in their environment.
Kentucky Core Academic Standards – Science
Sixth Grade - MS. Matter and Energy in Organisms and Ecosystems
06-LS2-1. Analyze and interpret data to provide evidence for the effects of resource availability
on organism and populations of organisms in an ecosystem.
LS2.A: Interdependent Relationships in Ecosystems
Seventh Grade - MS. Growth, Development, and Reproduction of Organisms
07-LS1-4. Use argument based on empirical evidence and scientific reasoning to support an
explanation for how characteristic animal behaviors and specialized plant structures affect the
probability of successful reproduction of animals and plants respectively.
07-LS1-5. Construct a scientific explanation based on evidence for how environmental and
genetic factors influence the growth of organisms.
Eighth Grade - MS. Interdependent Relationships in Ecosystems
08-LS2-5. Evaluate competing design solutions for maintaining biodiversity and ecosystem
services.*
Eighth Grade - MS. Human Impacts
08-ESS3-3. Apply scientific principles to design a method for monitoring and minimizing a
human impact on the environment.*
ESS3.C: Human Impacts on Earth Systems
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Background
Stingrays are Fish
Stingrays are a type of fish. They live underwater, breath water through gills, have a protective
layer of scales and mucus covering their body, and are cold-blooded, or ectothermic.
Worldwide there are more than 22,000 species of fish. Stingrays fall into a special group of fish
known as cartilaginous fish including sharks, rays, skates, and guitarfish. This group has a
skeleton made of cartilage rather than bone like most fish known as bony fish. Bony fish have
gas-filled swim bladders that allow vertical movement in the water column. On the other hand,
stingrays do not have swim bladders. They either swim in the open water using their large
wing-like fins or use their flat bodies to hide under the sand. Using these wide fins, they also
have the ability to glide for long distances through the water. Looking at the cart below, you
can see the differences between cartilaginous fish and bony fish.
http://www.sharkproject.org/haiothek/index_e.php?site=evolution
Cartilaginous fish (Chondrichthyes) Bony fish (Osteichthyes)
Skeleton
Cartilage
Wholly or partially ossified
Gill slit cover
Open gill slits
Gill cover
Swim bladder Not present
Present
Skin surface
Covered in scales
Covered in dermal teeth
Stingray Adaptations
Stingrays have several unique adaptations that help them survive in their environment. In
general, stingrays are darker on top and lighter below. This is a type of camouflage known as
countershading. Countershading aids many aquatic animals, including stingrays, as they are
more difficult to see because their light undersides blend in with the sunlight. The darker upper
body blends in with the ocean depths which are black as sunlight completely dissipates.
Stingrays also have the ability to blend in with their environment, being able to change their
colors when burrowing to hide from predators and prey. A flat body gives them the ability to
not only hide from potential predators, but to also hide form their prey. Stingrays also have
specialized sensory organs that detect electrical fields. These organs, called ampullae of
Lorenzini, aid stingrays in locating their prey by detecting tiny electrical signals from the prey’s
muscles. Stingrays have a protective spine at the base or middle of their tail. This is almost
always venomous so it inflicts a painful jab as well as administering potentially lethal venom.
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This is strictly used for the animal protecting itself. It is rare for a person to be injured by a
stingray, and it is rarely lethal. The venom does not affect humans that badly, and the barb
injury heals very quickly. When walking in sand in the ocean, make sure to shuffle your feet to
alert stingrays of your presence.
Stingray bodies come in a variety of shapes and sizes. These are adaptations to the
environment of that stingray species. A depressiform, or flattened, is adapted for living on the
bottom of the ocean, while a fusiform, or torpedo shape, is adapted for open water. Almost all
stingray species and relatives have this depressiform body shape. While a related animal like a
guitarfish have more of a shark like body, other species like a skate will have a diamond shaped
body and a long un-forked tail that aids in maneuverability as well as living near the bottom.
Stingrays can be solitary or in groups, usually for breeding and migration. Many larger species
will migrate all over the world, some migrate once a year in the thousands, and others will stay
in one reef or sand flat for their whole life.
Growth rates in rays, just like sharks, are a bit of a mystery. Studies show that even though
their cartilage structure is very similar to ours, it has a much different growth rate and pattern.
These studies also include the fact that it is hard to truly compare two types of animals when
they are vastly different. The closest comparison for their growth rates are those of small
mammals, like rats. The changes based on age and their cellular densities are rather similar. As
a rat or ray grows, they have a higher cellular density to help grow their skeletal structure.
When growing, they need less and less cellular density to help keep the skeleton growing. For
elasmobranchs it never truly stops, but greatly slows down.
Figure 1:
This is the current hypothesis on how the skeletal structure of a stingray mineralizes. Cellular
density slows down as the animal ages, showing that once the tesserae, which is the matrix that
makes the cartilage strong, forms fewer cells are needed. In mammals these cells would
completely disappear, but because elasmobranchs constantly grow more cells are needed over
time.
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http://onlinelibrary.wiley.com/enhanced/figures/doi/10.1111/j.1469-7580.2009.01116.x - figureviewer-f6
This means that sharks and rays do grow their whole lives. It is well documented that growth
rates in ectotherms are significantly affected by the amount of food intake. Radio carbon dating
could tell us more information about the ages of these animals, but it is sometimes difficult to
do and not always accurate. More recent studies are also showing that water temperature and
carbon dioxide levels may also affect the growth rate and potential as these factors can effect
metabolic rates. There is even some evidence that ocean acidification and warmer
temperatures may reduce the olfactory capabilities in elasmobranchs decreasing their hunting
capability.
Rays have one type of reproduction, called Ovoviviparity, or aplacental viviparity. This means
the rays have embryo sacs within the uterus, but bear live young. The young rely on the yolk of
the egg until it runs out. After this, the mother will produce uterine milk, with the fetus either
absorbing or ingesting it. Internal fertilization, which is what rays do, increases the sperm
retention. This insures that nothing is wasted and the fertilization process is more efficient.
Ovoviviparity differs from viviparity and oviparity by being more of a combination of both
processes. Viviparity is live birth where the embryo reaches complete development before birth
occurs and oviparity is egg laying.
Stingray Diets
Animal diets closely related to the dentition, or teeth, of those animals. Stingrays have a very
unique tooth structure. This aids them in eating what we believe is their normal diet.
Unfortunately, there is not a lot of information on what exactly stingrays and related species
eat, but we can infer that from their morphology and mouth placement about what they most
likely eat. Small fish, crustaceans, bivalves, worms, and other small animals living in the sand or
pelagic areas are thought to be common prey items. Stingrays and other related species have
flat, rough teeth that sit on a tooth band. They do replace these teeth similarly to how sharks
lose theirs. This is mainly because of the types of animals they feed on, which usually have very
hard shells to crunch through. Cartilage is not a very strong material, so the jaw of a stingray,
shark, skate, or guitarfish should not be that strong. Scientists discovered that when a stingray’s
skeletal system is forming, there is calcium added to the structure. Usually, calcium cannot be
moved unless there is blood present, but young rays have been found with large amounts of
calcium near their skeletal system as they grow. This calcium is added to the cartilaginous
structure as they age.
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Figure 2:
These are examples of a stingray’s teeth, or mouth plates.
Stingray Species
The Newport Aquarium currently displays a southern stingray, a honeycomb whiptail ray, a
mangrove ray, freshwater river rays, cownose rays, and yellow stingrays. Our largest tank is not
suitable for any manta species, as they can get well over 10-15 feet across. The smallest
stingrays stay right around a foot long and are desirable for the aquarium trade. Ours are called
yellow stingrays, which for maximum size might get around 2 feet across. All together, there are
around 500 species of stingrays and skates across 18 separate families.
Relationships
Stingrays have mutualistic, parasitic, and commensal relationships with other animals in the
ocean. Their mutual relationship comes in the form of fish that swim above them as they search
for food. When stingrays eat, they do not always consume everything that they find. The fish
that follow them eat the leftover fish that the stingray did not want. This benefits the fish, but
does not alter the stingray’s life in any way. Parasites can be found on or in almost any animal
on earth, so the stingray is no exception. Parasites feed while harming the host in some way.
Whether this be feeding from the host or laying eggs in them, it is deteriorating and in some
cases ends in the death of the host. The commensal relationship is also with a species of fish
called cleaner wrasses and other smaller species. Stingrays are not particularly clean animals,
and cannot remove the parasites or mucus that covers them. These small fish will create
cleaning stations to help remove unwanted guests on the stingrays. This benefits both parties,
with the fish getting a meal and the stingray being cleaned off. These are all symbiotic
relationships between two or more animals.
Food Web Connections
Within food chains, there are many levels, from producer to apex predator. Stingrays sit right in
the middle. They are predators, but not top tier, apex predator. This puts them in a place where
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they eat prey but also regularly become prey. Apex and secondary predators eat stingrays. Apex
predators consume tertiary and/or secondary consumers, which consume primary consumers,
which consume producers, which produce energy from the sun through photosynthesis. The
main source of energy for all ecosystems initiates from the sun in the form of solar energy.
Through the process of photosynthesis, plants convert this energy into oxygen and glucose.
Because of this conversion, green plants, some bacteria, an algae are labeled as producers. An
animal, such as an herbivorous fish, who consumes the plant, is known as a primary consumer,
because it receives the energy from the plant, which converted the energy from the sun. The
stingray who eats the fish that feeds on the plant that converted the sunlight is known as a
secondary consumer, hence a process that directly relates back to the sun as the primary
energy source. Stingrays help keep the balance within ecosystems predator and prey
relationships.
A stingray’s most sophisticated predator is that of the hammerhead. Hammerheads have a
special head shape that allows them to scan for rays, skates, and guitarfish hiding under the
sand. Though a ray is flattened to give them a hiding place, hammerheads developed a
cephalofoil with extra sensory organs to locate any living creature around them. This head
shape can also aid in making sure that prey cannot get away, pinning it to the ocean floor.
Stingray Conservation
Stingrays are vital to the ecotourism and education opportunities available in the Cayman
Islands. Here, snorkelers have the chance to feed, touch, and swim with them. Not only does
this give guests a chance to interact with an amazing animal, but also they get to learn about
their importance in their ecosystems and why they need protection. The Sandbar and Stingray
City both are home to large amounts of southern stingrays (Hypanus americana) which granted
an opportunity to study stingrays. At these locations, they learned that there are six times more
females than males visiting these places, along with an estimated group size of around 150
individuals. In addition, they discovered much about their breeding habits, habitat size varying
from male to female and genetic data to further our comparison to other species.
The International Union for Conservation of Nature deems most stingray species as DD, or data
deficient. This means there is not enough known about a species to say that there is a risk of
extinction. More groups need to be studying stingrays and their behaviors in the wild to help us
better understand what is happening with them.
Finally, WAVE is assisting the O’Seas Conservation Foundation in Shark Science and Youth
Education. By integrating shark tagging with youth education, this innovative approach will
enhance our knowledge pertaining to an understudied species and will help to secure our
future through the education and motivation of our environmentally conscious youth. Due to
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the similarities between many sharks and stingrays, this information can help out more than
just shark conservation.
Vocabulary
Conservation – The study of the loss of Earth’s biological diversity and ways this loss can be
prevented
Depressiform – flattened or dorso-laterally compressed
Ectotherms – Animals that need an external body heat source
Fusiform – torpedo shaped, tapering at both ends
Homocercal – forked, appearing outwardly symmetrical but with the backbone passing into the
upper lobe
Limiting factor - A factor present in an environment that controls a process, particularly the
growth, abundance or distribution of a population of organisms in an ecosystem
International Union for Conservation of Nature – IUCN, the global authority on the status of the
natural world and the measures needed to safeguard it
Metablolism – chemical processes within an organism that sustain life
Mineralize – converting organic matter into a mineral or inorganic material/structure
Morphology - the branch of biology that deals with the form of living organisms, and with
relationships between their structures.
Mutualism - two organisms of different species exist in a relationship in which each individual
benefits from the activity of the other.
Ocean acidification - a reduction in the pH of the ocean over an extended period time, caused
primarily by uptake of carbon dioxide from the atmosphere.
Oviparity - producing eggs that mature and hatch after being expelled from the body
Ovoviviparity - producing eggs that are hatched within the body, so that the young are born
alive but without placental attachment
Photosynthesis - process by which green plants and some other organisms use sunlight to
synthesize foods from carbon dioxide and water.
Play behavior - activities performed for self-amusement that have behavioral, social, and
psychomotor rewards
Radiocarbon dating - a technique for determining the age of organic materials, based on their
content of the radioisotope carbon 14 acquired from the atmosphere.
Symbiotic - organisms that live together; however, the relationship is not necessarily beneficial
to both. (ie parasite-host)
Viviparity - development of the embryo inside the body of the mother, eventually leading to
live birth
Extension Activities
Project WILD Activities. Please contact your state Project WILD coordinator for more
information. See http://projectwild.org/KentuckyCoordinator.htm (for Kentucky) or
http://www.projectwild.org/ProjectWILDCoordinators.htm (for other states).
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Bearly Growing – Students will compare similarities and difference between the growth
of black bears and humans.
Bottleneck Genes – Students will (1) describe biodiversity as it relates to natural
systems, species, or individuals; (2) articulate that genetic diversity is essential to the
health of a species because it facilitates adaptation to change and provides sources for
new genetic material; (3) explain how natural selection favors individuals with traits
adapted to their environment; and (4) explain that for a wildlife population to sustain
itself, there must be enough habitat to support a healthy-sized population that will carry
a healthy-sized gene diversity.
Career Critters – The students will (1) identify five examples of how wild animals and
plants can be used to manage some environmental problems, and (2) describe and give
examples of an organism and its niche.
Carrying Capacity – Students will (1) formulate and test hypotheses related to wildlife
populations and carrying capacity, and (2) describe the significance of carrying capacity.
Changing Attitudes – Students will (1) give an example of a chance in attitudes related to
a wild animal or the environment, and (2) describe factors that may influence changes in
attitudes.
Ecosystem Facelift – Students will (1) describe interactions or interdependency of
organisms within an ecosystem; (2) articulate that managing an ecosystem as a whole,
and not just for one or a few species, is essential for ensuring ecosystem diversity; and
(3) relate the increase of wildlife populations to the improvement of habitats.
Ethi-Reasoning – Students will (1) examine their own values and beliefs related to
wildlife and other elements of the environment, (2) listen to and respect the right of
other to maintain different values and beliefs, and (3) evaluate possible actions they
might take that have an effect on wildlife and the environment.
Litter We Know – Student will (1) identify and evaluate ways that litter pollution can
endanger wildlife, and (2) propose ways to help eliminate these dangers to humans and
wildlife.
Oh Deer! – Students will (1) identify and describe food, water, and shelter as three
essential components of habitat; (2) describe factors that influence carrying capacity; (3)
define “limiting factors” and give examples; and (4) recognize that some fluctuations in
wildlife populations are natural as ecological systems undergo constant change.
Resources
WAVE Foundation - http://www.wavefoundation.org
Project Wild - http://www.projectwild.org
Project Wet - http://www.projectwet.org
Project Learning Tree - http://www.plt.org
Stingray Jaw information - http://www.sciencemag.org/news/1998/09/death-soft-jaws-stingray
Endangered Species Information http://education.nationalgeographic.org/media/endangered/
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Conservation Efforts - http://wavefoundation.org/conservation/conservation-fund/
Stingray Data - http://onlinelibrary.wiley.com/doi/10.1111/j.1469-7580.2009.01116.x/full
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