Fish & Invertebrate Taxonomy & Natural History Flashcards
Give the scientific names of the sharks commonly kept in managed care:
- Nurse shark
- Sand tiger shark
- Sandbar shark
- Blacktip reef shark
- Bonnethead shark
- Leopard shark
- Zebra shark
- Whitespotted bamboo shark
- Whale shark
- Hammerhead shark
Common Sharks in Human Care
- Nurse shark – Ginglymostoma cirratum
- Sand tiger shark – Carcharias Taurus
- Sandbar shark – Carcharhinus plumbeus
- Blacktip reef shark – Carcharhinus melanopterus
- Bonnethead shark – Sphyrna tiburo
- Leopard shark – Triakis semifasciata
- Zebra shark – Stegostoma fasciatum
- Whitespotted bamboo shark – Chiloscyllium plagiosum
- Whale shark – Rhincodon typus
- Hammerhead shark – Sphyrnidae spp.
Describe the unique structure of elasmobranch skin.
What type of scales do they have?
How does skin thickness vary with species?
What about rays? What about Chimaeras?
What defensive mchanisms do they have in the integumentary system?
What sensory organs do they have within their skin?
Integument
- Placoid scales (aka dermal denticles) - formed like teeth (calcified layer, dentin, enamel)
- Silk sharks - denticles minute (softer skin); Blue sharks - females have sig. thicker skin d/t mating trauma
- Many rays have few to no scales - tend to have sig. mucus layer
- Porcupine rays and some others - “armor” on dorsum
- Many batoids, some sharks - sharp spines; venomous spine or barb in most rays (except mantas, mobulas, porcupine rays); can have more than one barb
- Barbs covered by integument including cells for venom production
- Chimaeras - scaleless (except juveniles), very sensitive to skin trauma
- Visible, symmetrical epithelial pores
- Pit organs - free neuromasts; sensory hair cells detect water motion
- Ampullae of Lorenzini - gel-filled tubular structures, detect electric fields for navigation, prey/predator detection, mating
Describe the unique adaptations of the elasmobranch muculoskeletal system.
How does their skeleton differ from other vertebrates?
Describe the feeding mechanisms.
What sharks have red muscle? What is its function?
Musculoskeletal System
- Entire endoskeleton cartilaginous - made of hyaline cartilage-like core supported by mineralized tesserae
- Bone exists - teeth, denticles
- Calcification can occur in vertebrae, jaws; true bone not present
- Centrum of vertebral cartilage can be used for aging
- If cartilage fractures - does not heal fully, fibrous “bandage”
- Prey capture - biting, ram feeding and/or suction feeding
- Permanent jaw protrusion assoc. w/ spinal deformity in sand tiger sharks
- Muscle similar to teleosts (red, white) - most poikilothermic but regional endothermy in some lamniform sharks (mako, white, salmon, porbeagle, thresher sharks)
How do elasmobranchs regulate their buoyancy?
Buoyancy
- Buoyancy d/t cartilaginous skeleton, large lipid-dense liver, urea and methylamine oxides in blood
- No cartilaginous fish have swim (gas) bladders; sand tiger sharks swallow air for additional buoyancy
Describe the anatomy of the elasmobranch eye.
What species have mobile eyes?
Describe the ray iris?
How does the PLR differ across species?
How do sharks adjust their tapetum?
What makes enucleation more challenging in elasmobranchs than in teleosts?
What species have the pinneal eye?
Ocular Anatomy
- Diverse eye anatomy - typically fixed eyelids (mobile in some - nurse and catsharks) - is blink reflex
- 3rd eyelid in some (requiem sharks)
- Pupil type and shape characterizing features in some
- Rays - upper iris modified into operculum pupillare covers iris during light adaptation
- PLR highly variable - diurnal –> rapid constriction, nocturnal –> intermediate, batoids –> slowest
- Dilation can be achieved w/ topical acetylcholine
- Sclera - thick w/ cartilaginous layer; Cornea - same layers as other vertebrates
- Many sharks - partially or totally occlusible tapetum - melanophores can migrate (some have fixed tapetum - catsharks, deep-sea sharks)
- Avascular retina, no choroid gland
- Many can pull globe into socket w/ extraocular muscles
- Optic pedicle - cartilaginous structure - connects globe to cranium
- D/t scleral cartilage, optic pedicle and size of optic nerve/vessels/muscles - enucleation more challenging
- Pineal organ/eye (epiphysis) well-developed in most (except absent in electric rays)
- Photoreceptors superficial on dorsal chondrocranium
Describe the auditory anatomy of sharks?
Auditory Anatomy
- Ears similar to other vertebrates
- Located in cartilaginous otic capsules caudal to large optic capsules; only external indication of position is tiny paired endolymphatic pores on dorsal chondrocranium near medial line
- Each ear - inner ear labyrinth (utriculus, sacculus, lagena) - none of accessory organs seen in teleosts
- W/in endolymphatic duct - no otolith, instead otoconial paste of CaCO3 granules in gel functioning like otoliths in teleosts
- Patches of sensory epithelium (macula neglecta) - vibration detection
- Audiograms - freq. 50-1500 Hz, greatest sensitivity 400-600 Hz (may be sensitive to pump/filters noise)
