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Chondrichthyan (, skates, rays) Announcements

1. Please review the syllabus for reading and lab information! 2. Please do the readings: for this week posted now. 3. Lab sections: 4. i) Dylan Wainwright, Thursday 2 - 4/5 pm ii) Kelsey Lucas, Friday 2 - 4/5 pm iii) Labs are in the Northwest Building basement (room B141) 4. Lab sections done: first lab this week on Thursday! 5. First lab reading: Agassiz story; lab will be a bit shorter 6. Office hours: we’ll set these later this week Please use the course web site: note the various modules Outline

Lecture outline: -- Intro. to chondrichthyan phylogeny -- 6 chondrichthyan defining traits (synapomorphies) -- 3 chondrichthyan behaviors -- Focus on several major groups and selected especially interesting ones 1) Holocephalans ( or ratfishes) 2) (sharks, skates, rays) 3) Batoids (skates, rays, and ) 4) Sharks – several interesting groups

Not remotely possible to discuss today all the interesting groups! tree – key ―fish‖ groups

Today Chondrichthyan Fishes

sharks Overview: 1. Mostly marine 2. ~ 1,200 518 species of sharks 650 species of rays 38 species of chimaeras Skates and rays 3. ~ 3 % of all ―fishes‖ 4. Internal made of 5. Three major groups 6. Tremendous diversity of behavior and structure and function

Chimaeras Chondrichthyan Fishes: 6 key traits

Synapomorphy 1: dentition; replacement pattern

• Teeth are not fused to • New rows move up to replace old/lost teeth • Chondrichthyan teeth are diverse in shape and size • Similar in overall structure to mammalian teeth Chondrichthyan Fishes: 6 key traits

Synapomorphy 1: dentition; tooth replacement pattern Chondrichthyan Fishes: 6 key traits

Synapomorphy 1: dentition; tooth replacement pattern

Helicoprion Chondrichthyan Fishes: 6 key traits

Synapomorphy 2: placoid scales

Dermal denticles: ―tiny skin-teeth‖ or scales Chondrichthyan Fishes: 6 key traits

Synapomorphy 2: placoid scales

Mammalian tooth

~130 um Chondrichthyan Fishes: 6 key traits

Synapomorphy 2: placoid scales Chondrichthyan Fishes: 6 key traits

Synapomorphy 2: placoid scales "riblets"

Biomimetic surfaces

Speedo swim suits Shark skin as inspiration Chondrichthyan Fishes: 6 key traits Synapomorphy 3: prismatic calcification of cartilage

Shark cartilage is *not* like the cartilage in your body, and is also not a ―miracle cure‖

© Mason Dean

Tesserae: ―Tiles‖ of mineralized cartilage Also, skeleton () has no sutures Chondrichthyan Fishes: 6 key traits Synapomorphy 4: structure

Ceratotrichia: unsegmented bundles of collagenous fibers that make up fin rays Chondrichthyan Fishes: 6 key traits Synapomorphy 4: fin structure

Ceratotrichia: unsegmented bundles of collagenous fibers Chondrichthyan Fishes: 6 key traits Synapomorphy 5:

WATER Pore

Canal—filled with conductive jelly

Electroreceptive Cells Nerve Chondrichthyan Fishes: 6 key traits Synapomorphy 5: Ampullae of Lorenzini Passive

Ampullae of Lorenzini Chondrichthyan Fishes: 6 key traits Synapomorphy 5: Ampullae of Lorenzini

Ampullae of Lorenzini Chondrichthyan Fishes: 6 key traits Synapomorphy 5: Ampullae of Lorenzini

Electroreception

Ampulla of Lorenzini: detect electric fields Chondrichthyan Fishes: 6 key traits Synapomorphy 5: Ampullae of Lorenzini

Dogfish shark: Pores extend across head

Round ray (A) and Bat ray (C): Pores extend across body, cluster around mouth Chondrichthyan Fishes: 6 key traits

Synapomorphy 6: Pelvic claspers in males

male

Internal fertilization

Chondrichthyan Fishes: 3 key elasmobranch behaviors Behavior 1: Feeding

(Great) white shark Chondrichthyan Fishes: 3 key elasmobranch behaviors Behavior 1: Feeding

Basking shark filter feeding Chondrichthyan Fishes: 3 key elasmobranch behaviors Behavior 1: Feeding

Angel shark suction feeding Chondrichthyan Fishes: 3 key elasmobranch behaviors Behavior 2: Locomotion shapes

Heterocercal

Homocercal Chondrichthyan Fishes: 3 key elasmobranch behaviors Behavior 2: Locomotion

Spiny dogfish swimming (seen from below) Chondrichthyan Fishes: 3 key elasmobranch behaviors Behavior 2: Locomotion

Bamboo shark swimming (seen from behind) Chondrichthyan Fishes: 3 key elasmobranch behaviors Behavior 3:

Great diversity in chondrichthyan reproductive patterns

OVIPARITY (-laying) (live )

Skates & some sharks Rays & some sharks Chondrichthyan Fishes: 3 key elasmobranch behaviors Behavior 3: Reproduction

Some species exhibit Intrauterine cannibalism: most have 2 uteri and embryophagy/ occurs in each – ultimately only 1 pup born from each .

Ovoviparous – another reproductive mode

Embryo egg eating (oophagy) Chondrichthyan Fishes: diversity

Carcharhiniiformes

Lamniiformes Sharks

Orectolobiformes

“other” sharks

Batoidea Skates & Rays

Chimaeriformes Chimaeras

modified from Human et al. 2006, Molecular and Evolution Chondrichthyan Fishes: diversity Group 1: Chimaeras

• Holocephalians (synapomorphies = unique structure, covered , tooth plates), also known as ratfish, ghost sharks, rabbitfish • No stomach, venomous spine; ever-growing tooth plates that protrude like a rodent’s incisor teeth • date back to early • diverged from sharks around 400 million ago

More basic facts – see book -- poisionous dorsal spine ??? Chondrichthyan Fishes: diversity Group 1: Chimaeras

Tenaculum: present in males, and used for reproduction to somehow interact with females

tenaculum

Movie of ratfish swimming Chondrichthyan Fishes: diversity Group 1: Chimaeras

• Oviparous – time unknown • no parental care • oviducal gland secretes case around fertilized egg • 2 oviducal glands produce 2 egg cases simultaneously • egg case hardens (“tans”) in

Fossil egg case from Chondrichthyan Fishes: diversity Group 2: Elasmobranchii: sharks, skates, and rays

Elasmobranchii Carcharhiniiformes

Lamniiformes Sharks

Orectolobiformes Squaliformes

“other” sharks

Batoidea Skates & Rays

Chimaeriformes Chimaeras

modified from Human et al. 2006, and Evolution Chondrichthyan Fishes: diversity Group 2: Elasmobranchii: sharks, skates, and rays Chondrichthyan Fishes: diversity Group 2: Elasmobranchii: sharks, skates, and rays

Synapomorphy 1 (of 1): Unique structure elasmos (Greek for "metal plate") and branchus (Latin for "gill") Chondrichthyan Fishes: diversity Group 2: Elasmobranchii: sharks, skates, and rays

Carcharhiniiformes

Lamniiformes Sharks

Orectolobiformes Squaliformes

“other” sharks

Batoidea Skates & Rays

Chimaeriformes Chimaeras

modified from Human et al. 2006, Molecular Phylogenetics and Evolution Chondrichthyan Fishes: diversity Group 3: Batoids: skates, rays, and sawfish

54 million years ago Today

Batoids: a very conservative body shape over a long evolutionary time frame Chondrichthyan Fishes: diversity Group 3: Batoids: skates, rays, and sawfish

Batoid anatomy: dorso-ventral compression Chondrichthyan Fishes: diversity Group 3: Batoids: skates, rays, and sawfish Chondrichthyan Fishes: diversity Group 3: Batoids: skates, rays, and sawfish ray

What are the differences between rays (left) and skates (right)? ―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 in hard rectangular cases sometimes called "mermaid´s purses". Also, skates typically have a prominent dorsal fin while the dorsal fin is absent or greatly reduced in rays. ‖

―Most rays are kite-shaped with whip-like possessing one or two stinging spines while skates have fleshier tails and lack spines. Rays protect themselves with these stinging spines or barbs while skates rely on thorny projections on their backs and tails for protection from predators. Skates have small teeth while rays have plate-like teeth adapted for crushing prey. Another difference is that rays are generally much larger than skates. ‖ FMNH website Chondrichthyan Fishes: diversity Group 3: Batoids: skates, rays, and sawfish Pristidae: ―sawfish‖

All species are

A special note on Sawfish: They are not sharks – they are rays! Chondrichthyan Fishes: diversity Group 3: Batoids: skates, rays, and sawfish

Rajidae (skates) • 200 species • Size: 30cm-2.4m • Oviparous

Photos, counterclockwise: binoculata, Raja clavata, Skate in egg case & with sac. Chondrichthyan Fishes: diversity Group 3: Batoids: skates, rays, and sawfish

Rhinobatidae ()

• 45 species • Size: 1.5-1.8m • Viviparous

White-spotted guitarfish djiddensis Bowmouth guitarfish

Chondrichthyan Fishes: diversity Group 3: Batoids: skates, rays, and sawfish & : electric rays ELECTRIC ORGANS: generate electric shocks used for & defense • 26 species • 21 species • Size: 15-66cm • Size: up to 200 lbs! • Viviparous • Viviparous • Electric organs: generate 8-37 volts • Electric organs: in largest, can generate 220 volts!

Lesser Leopard brasiliensis Torpedo panthera

Chondrichthyan Fishes: diversity Group 3: Batoids: skates, rays, and sawfish Dasystidae: stingrays

• 70 species • Size: 12cm-4m • Viviparous • Most with venomous spine(s)

Photos, left to right: Southern americana, Blue-spotted stingray Taeniura lymna Chondrichthyan Fishes: diversity Group 3: Batoids: skates, rays, and sawfish Myliobatidae: mantas and eagle rays

• 42 species • Size: Mantas ~8m! • Viviparous • Includes LARGE filter feeders & benthic predators

Photos, counterclockwise from top left: Manta birostris, Spotted narinari, and Cownose Ray bonasus Chondrichthyan Fishes: diversity Group 2: Elasmobranchii: sharks, skates, and rays

Selachii (sharks) Carcharhiniiformes

Lamniiformes Sharks

Orectolobiformes Squaliformes

“other” sharks

Batoidea Skates & Rays

Chimaeriformes Chimaeras

modified from Human et al. 2006, Molecular Phylogenetics and Evolution Chondrichthyan Fishes: diversity Group 4: sharks Rhincodontidae: shark Chondrichthyan Fishes: diversity Group 4: sharks Sphyrnidae: Hammerheads Chondrichthyan Fishes: diversity Group 4: sharks :

Isistius brasiliensis

Chondrichthyan Fishes: diversity Group 4: sharks Dalatiidae: Cookiecutter shark Chondrichthyan Fishes: diversity Group 4: sharks Dalatiidae: Cookiecutter shark Chondrichthyan Fishes: diversity Group 4: sharks Squatinidae: Angel sharks

Unusual for sharks – lower lobe of caudal fin is equal or larger than upper lobe Sit-and-wait predator (recall the suction feeding movie!) Chondrichthyan Fishes: diversity Group 4: sharks Pristiophoridae:

Convergent features but different from sawfish (): ~ smaller size ~ barbels Different from, but convergent ~ uneven, alternating sawteeth with, Pristidae, which are rays ~ gill slits on sides (not ventral)

Use snout to slash at prey Electro-receptive barbels prey in substrate Chondrichthyan Fishes: diversity Group 4: sharks Mitsukirinidae:

Mitsukurina owstoni Chondrichthyan Fishes: diversity Group 4: sharks

Mitsukirinidae: Goblin shark Chondrichthyan Fishes: diversity Group 4: sharks

Mitsukirinidae: Goblin shark Chondrichthyan Fishes: diversity Group 4: sharks Alopiidae:

Tail is nearly as long as the rest of the body

Hunt schooling fish by slapping and stunning them with their tails Chondrichthyan Fishes: diversity Group 4: sharks Cetorhinidae:

Filter feeding

Up to 40 ft (12 m) long

Migrate following blooms

Many historic ―-monster‖ sightings are thought to be basking shark remains (below from 1868) Chondrichthyan Fishes: diversity Group 4: sharks : sharks; white sharks

Counter-current heat exchangers () endothermy, to warm swimming musculature

White shark varies by population: Grey/silver = North America Brown/copper = Black =

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