Lecture 4. - Wednesday, September 3, Discuss next weekend - Illinois River Trip - Who can make it? 2. Discuss Fish Friday presentations - Sign up for Slots 3. Distinguishing Traits of Chondrichthyes 4. Traits that Distinguish Elasmobranchii & Holocephali 5. SHARKS & RAYS a. ecology & life-history b. reproduction c. conservation d. notable shark & ray orders

IB Student Picnic Hosted by the School of Integrative Biology Thursday, Sept PM Illini Grove Pavilion (corner of Lincoln and Pennsylvania Ave) Free Food Free T-shirt Meet Faculty Find out what SIB is all about and meet other IB majors!

Illini Grove Pavilion 5-8 pm Food served 5:30 to 7:30 pm Hamburgers, cheeseburgers, veggie burgers Ranch beans, potato salad, watermelon Cookies Pop and water RSVP to Debbie Lanter, or

Chondrichthyes synapomorphies 1. Pelvic claspers Derived from the margin of the pelvic fin

Mating Sharks Video 1 Mating Sharks Video 2 Cool Shark Videos to Checkout

Chondrichthyes synapomorphies Teeth not fused to jaws Replaced serially in whorls

Chondrichthyes synapomorphies 3. Skull (chondrocranium) lacks sutures

Elasmoid Ganoid Placoid Cosmoid 9 bone dentine enamel

heterocercal abbreviated heterocercal homocercal isocercal 8

Bull Shark with heterocercal tail

Major living gnathostome lineages

Subclass Holocephali Ratfishes, rabbitfishes, or chimeras Order Chimaeriformes (58 species)

Subclass Holocephali Ratfishes, rabbitfishes, or chimeras

Subclass Holocephali lacking gill slits - a single gill covering over 4 gill openings Upper jaw fused to cranium skin is naked in adults Some males have cephalic claspers in addition to pelvic ones Differ from sharks and rays by:

Order Chimaeriformes Ecology, Life History Reproduction, oviparous (egg-laying), internal fertilization Benthic, deep sea (80 to 2600 m), around the world Nocturnal Feed mainly on benthic invertebrates

mermaid’s purses

Lemon Shark Giving Birth

Whale Shark

whale shark video N39LJIhttp:// N39LJI

goblin shark

megamouth

megamouth video mnZv8Qhttp:// mnZv8Q start at 2:10

thresher shark (Alopiidae)

thresher shark video VRMFQhttp:// VRMFQ start at 5:30

basking sharks

great white shark

great white shark video OCqoohttp:// OCqoo

Order Carcharhiniformes (ground sharks) Family Carcharhinidae (requiem sharks) Largest Order - 8 families, 210 species Tiger shark Hammerhead shark

Order Carcharhiniformes (ground sharks) Family Carcharhinidae (requiem sharks) Bull shark Oceanic white tip shark Silky shark

Shark attacks on humans 35 to 55 unprovoked attacks each year 6 to 11 fatalities per year 54% of attacks on surfers/windsurfers 38% on swimmers/waders 6% on divers/snorkelers Regions with most shark attacks:

Shark attacks on humans 35 to 55 unprovoked attacks each year 6 to 11 fatalities per year 54% of attacks on surfers/windsurfers 38% on swimmers/waders 6% on divers/snorkelers Regions with most shark attacks: South Africa - 63 attacks from 1990 to 2003 Brazil - 57 “ “ “ “ Australia - 51

Shark attacks on humans 35 to 55 unprovoked attacks each year 6 to 11 fatalities per year 54% of attacks on surfers/windsurfers 38% on swimmers/waders 6% on divers/snorkelers Regions with most shark attacks: South Africa - 63 attacks from 1990 to 2003 Brazil - 57 “ “ “ “ Australia - 51 Florida - 311

dogfish sharks (Squalidae) dogfish shark

saw sharks pointed snout used to thrash and incapacitate small fishes

electric rays (Torpedinidae)

sawfish (Pristidae)

More sawfish pictures

Skates (Rajidae)

Myliobatiformes Sting rays (Dasyatidae)

Myliobatiformes Sting rays

Myliobatiformes Manta rays (Myliobatidae)

Weblinks: great white : megamouth: thresher: hammerhead: sawfish: manta ray: for ground and requiem sharks (family Carcharinidae), skates (family Rajidae), and sting rays (Dasyatidae) go to the following website and look up some details about one or two species. There is tons of really cool stuff on sharks at the Florida Museum of Natural History website. We could spend a lot of time on each of the various orders and families in the Elasmobranchii. Instead, I want you to look up something about each of the following groups. Find one or two facts that are of interest to you.

Review Questions 1. List the characters that distinguish between Elasmobranchii and Holocephali. Who are the Elasmobranchii and who are the Holocephali? Where do Holocepahli generally live? 2. We covered a lot of sharks and rays in a short amount of time. For each of the following groups, list one or two interesting facts about their biology. You can use your book, any book in the library, or the links I provided on the powerpoint file. 3. Describe the adaptations that Elasmobranchs have for maintaining neutral buoyancy. Explain how they work. 4. One could argue that Elasmobranch life-history reflects selection for high efficiency in their use of resources. What evidence supports this notion? Discuss both the life-history data (clutch sizes, when they mature, lifespan) as well as data on metabolism and feeding rates. 5. Although all Chondrichthyes have internal fertilization, they vary quite a bit in the development of the embryos. Describe this variation (oviparity, retained oviparity, ovoviviparity (and the variations on this theme), placental viviparity, and uterine viviparity). Can you propose a general model for how these reproductive strategies evolved?

Review Questions Cont’d. 6. Why can sharks hunt so good at night? Hint: what sensory systems are well-developed in this group. 7. How does the general pattern in Elasmobranch life-history predispose them to being easily overharvested and endangered? What is the general pattern for shark fisheries? How do other fisheries endanger shark populations?