1. RAYS AND SKATES UPCLOSE!
Good morning / welcome
Purpose of Sawfish In Peril:
To educate students about sawfish basics, biology, conservation, and research
Organization of presentation:
“Sawfish In Peril” is produced by the Florida Program for Shark Research/Florida Museum of Natural History. The presentation is based on the “Most Commonly Asked Sawfish Questions” section of the Museum’s Ichthyology web site-
Overview of presentation:
This presentation is approximately 45 minutes in length and should be presented in a question/answer format as presented on the web page.
FLORIDA PROGRAM FOR SHARK RESEARCH
Florida Museum of Natural History

2. Rays and Skates Upclose!
Ray and Skate Basics
Ray and Skate Biology
Ray and Skate Conservation
Ray and Skate Research
Use this time to ask the audience if they know what sawfishes are and anything they might know about these unique fish.
The presentation is presented in four sections:
Sawfish Basics
Sawfish Biology
Sawfish Conservation
Sawfish Research

3. RAY AND SKATE BASICS
We will begin by learning the basic facts about sawfishes, then move on to sawfish biology, conservation, and ongoing research.

4. What is a ray?
© George Ryschkewitsch
The common name sawfish refers to any member of the family Pristidae (the sawfishes). Despite their shark-like form and manner of swimming, they are rays (batoids). These large to huge-sized rays are characterized as having an elongate blade-like snout (rostrum or saw) that has laterally placed tooth-like denticles (rostral teeth) set into sockets. Sawfishes traditionally inhabited all coastal tropical and subtropical waters, including estuaries and river systems.
Rays are dorsoventrally flattened fish that are closely related to sharks.
All are considered to be within a closely related group of fish called elasmobranchs.
Rays belong to three scientific orders - Pristiformes, Myliobatiformes, and Torpediniformes

5. What is a skate?
© George Burgess
There are seven recognized species living worldwide today with some species that appear very similar to each other. However, this group of elasmobranchs is currently under taxonomic review, and the total number of species may decrease in the near future. The sawfishes are represented by the genera Pristis and Anoxypristis.
Skates are dorsoventrally flattened fish that are closely related to sharks.
All are considered to be within a closely related group of fish called elasmobranchs.
Skates are classified in the order Rajiformes.

6. Are all rays considered stingrays?
The rostrum, often referred to as the "saw", is used during feeding and for defense. The saw is slashed in a side-to-side motion to dislodge invertebrates from the substrate and to stun schooling fishes. In addition, the sawfish can use its saw in defense against large predators such as sharks.
Stingrays are a type of ray, however not all rays are stingrays as this group also includes electric rays, butterfly rays, round rays, manta rays, guitarfish, and sawfish.

7. How many species of rays and skates are there?
There are approximately different species of rays and skates that are divided into 18 families when scientifically classified.
At one time, the smalltooth sawfish could be found along the southeast coast of the U.S., from New York south into the Gulf of Mexico. However, due to range reduction, the smalltooth sawfish now is only found off the Atlantic and Gulf coasts of Florida. The other species of sawfish found in U.S. waters is the largetooth sawfish which historically was limited to the Gulf of Mexico.

8. What are the differences between rays and skates?
Sawfishes are harmless to humans if left undisturbed. Humans are too large to be viewed as potential prey. Care must be taken when handling or approaching a sawfish of any size, as they may defend themselves when they feel threatened, using their rostrum to strike from side-to-side with considerable force.
The major difference between rays and skates is in their reproductive strategies.
Rays are live bearing (viviparous) while skates are egg laying (oviparous), releasing their eggs in hard rectangular cases sometimes called "mermaid´s purses".

9. How long have rays and skates existed?
Sawfishes are among the largest rays living today. They commonly reach 16.4 feet (15.0 meters) in length, attaining a maximum length of 24 feet (7.3 meters).
U.S. National Park Service
The fossil record of rays and skates dates back to the Lower Jurassic (150 million years ago).

10. Do rays and skates have bones?
© Cathleen Bester
Rays and skates have no bones, but instead have skeletons made of cartilage as do sharks.
Cartilage is tough and fibrous but not as hard as true bones.

11. How do rays and skates swim?
© Doug Perrine
These unique animals swim through the water by gracefully undulating the modified pectoral fins, appearing to fly through the water.
They sometimes make spectacular leaps from the surface of the water.

12. Are stingrays dangerous to people?
© Cathleen Bester
Stingrays have venomous spines along or near the base of the tail. The muscular whip-like tail can be lashed about quickly in defense.
Occasionally beach-goers will accidentally step on stingrays that are partially buried in the sand near the beach resulting in a painful, serious wound in the foot.

13. Where do rays and skates live?
Rays and skates live in oceans throughout the world.
Most rays and skates are benthic while some are pelagic.
Some rays live in freshwater habitats

14. Can rays and skates live in freshwater?
In Florida, the Atlantic stingray (Dasyatis sabina) is known to live in freshwater along the St. Johns River waterway as well as inland freshwater lakes.
These populations of the Atlantic stingray are unique in that they spend their entire lifecycle in freshwater.
Sawfishes are "ovoviviparous", meaning that young sawfishes grow from eggs retained within the mother. After the embryos are fully developed, the mother sawfish gives live birth with an average litter size of about 8 pups.
© Doug Perrine

15. RAY AND SKATE BIOLOGY Transition:
We will now learn more about the biology of sawfishes.
© Tobey Curtis

16. What are some adaptions of rays and skates?
The dorso-ventrally flattened bodies allow rays and skates to glide closely over the bottom sediments in search of prey.
Their eyes and spiracles are positioned on the top of the head, allowing them to take in water for respiration while partially buried in the sand.
The mouth is located on the underside of the animal as an adaptation for feeding on benthic invertebrates and fishes.
No, sawfishes and all other fishes belonging to the class Chondrichthyes lack true bone, but rather have cartilaginous skeletons.
Cartilage is a type of connective tissue strong enough to give support (it is calcified but not ossified) but softer than true bone. Cartilage is found in the human ear and nose. Due to cartilage being softer than bone, it is very rare to find complete fossil remains of elasmobranchs.
© George Burgess

17. What does ray and skate skin feel like?
The skin feels exactly like sandpaper because it is made up of tiny teeth-like structures called dermal denticles.
Skate skin may also possess thorns which help to defend them from predators.
They have pectoral fins (fused to the head/trunk), pelvic fins, two dorsal fins, and a caudal fin. Like the great majority of rays, sawfishes lack an anal fin. Sawfishes have both a first dorsal fin and a second dorsal fin of roughly equal sizes. As far as the caudal fin is concerned, one species has both lobes well-developed, two species (plus the nominal species, Pristis pristis) has well-developed upper lobe and only a moderately developed lower caudal lobe, and three species have only a well-developed upper caudal fin lobe.

18. Do rays and skates have good vision?
It has been estimated that these animals live up to 25 to 30 years, reaching maturity at 10 years.
© Doug Perrine
The eyes of rays and skates are located dorsally, on the upper surface of the animal, while the mouth is located on the underside.
It is believed that vision may play only a secondary role in prey location and feeding behaviors.

19. How do rays and skates detect prey?
© George Burgess
Ampullae of Lorenzini on a sandbar shark
Sawfishes feed on small fishes and invertebrates that can be ingested whole through the mouth. They only feed on prey that can fit into their small mouths since they are unable to tear chunks off prey items with their toothy saw.
Rays and skates use the senses of smell (chemoreception), vision, hearing, the lateral line system, and electroreception (ampullae of Lorenzini) for capturing prey.
The lateral line system, which most fish possess, allows them to detect waves of pressure or mechanical disturbances in the water.

20. What do rays and skates eat?
The majority of rays and skates feed on bottom dwelling (benthic) animals including shrimps, crabs, oysters, clams and other invertebrates.
Some rays such as the manta and devil rays are filter feeders relying on plankton as their food source.

21. Do rays and skates have any predators?
Sharks, in particular hammerheads, often have spines in their digestive tracts and imbedded in their jaws from feeding on stingrays.
Adult sawfishes have very few predators. Crocodiles, large sharks, and even marine mammals such as dolphins are known predators of juvenile sawfishes. A large piece of an adult sawfish saw was reported from the stomach contents of a large tiger shark.
© George Burgess

22. How can you distinguish a male from
a female ray or skate?
Male rays and skates (as well as sharks) have claspers while females do not.
Claspers are modifications of the pelvic fins and located on the inner margin of the pelvic fins. They are used to transfer sperm to the female during mating.

23. Do rays and skates give live birth or lay eggs?
Rays give live birth while skates lay eggs in egg cases (as pictured above) referred to as "mermaid's purses".
© George Burgess

24. Do rays and skates take care of their young?
Neither rays or skates exhibit parental care other than moving to a protective area to lay eggs or give birth.
© James Sulikowski

25. RAY AND SKATE RESEARCH Transition:
Sawfishes are a part of our natural biodiversity and the ecological balance of aquatic habitats. Since we should protect and conserve this balance, we have included a section on the conservation of sawfish with a focus on sawfishes in the U.S. This is especially important since the smalltooth sawfish has recently been listed as “Endangered” and as such, is protected under the Endangered Species Act.
© Christina Conrath

26. What are some current ray and skate-related research projects?
© Christina Conrath
Tagging and tracking rays in some of the waterways along the coast of Florida. The data from this project will assist in the identification of daily and seasonal movements of rays.
The reproductive biology of skates and the feeding ecology of rays and skates in the Pacific Ocean.
The age and growth of a skate species that has declined more than 95% due to take as bycatch in the New England groundfisheries.

27. RAY AND SKATE CONSERVATION
© Doug Perrine

28. Are rays and skates threatened or endangered?
Unfortunately, there are many species of rays and skates that are considered threatened and endangered.
The IUCN Red List includes 547 species of elasmobranchs of which at least 20% are in danger of extinction.

29. FLORIDA PROGRAM FOR SHARK RESEARCH Florida Museum of Natural History
Further Information:
FLORIDA PROGRAM FOR SHARK RESEARCH
Florida Museum of Natural History