MARINE STUDIES CONSORTIUM (MSC) BIOLOGY OF FISHES SPRING 2010

Instructor: Dr. D. Rae Barnhisel; 603-878-3671; drbfishes@comcast.net

Location: New England Aquarium (NEAq) Learning Lab, Education Dept. Dates: Tuesdays, January 19 to May 4, 2010 Class Hours: 5:00–9:00 pm Office Hours: Before and after class; also by email and phone NEAq Assistant:Dan Laughlin, Fishes Dept. Asst. Curator; 619-973-0299; dlaughlin@neaq.org

Administration: Roger Stern, MSC Executive Director, 781-444-3643; rstern@princeton.edu 152 Maple Street, Sherborn, MA 01770

Weather Alert www1.assumption.edu/msc/weather.html and/or home.comcast.net/~drbfishes COURSE SCHEDULE: Week Fishes of Focus Related Topics Date Assignments Due Exams break Assignments/Exams Returned Activity Week 1 Course Overview Aquarium Overview Jan. 19 Vertebrate Classification NEAq Mapping Week 2 Early Fishes: Form and Function Jan. 26 fossil fish and lamprey Cladogram Exercise Week 3 Chondrichthyes: Comparative Anatomy Feb. 2 sharks and rays Tree and Label Practice Written Report Topic due Week 4 Early Osteichthyes: Review Feb. 9 lungfish and sturgeon Exam 1 Written Report Topic returned Week 5 Early Teleosts: bonytongues, Internal Anatomy Feb. 16 eels, and herring Dissection 1 Exam 1 returned Week 6 Ostariophysans: minnows, Aquatic Respiration Feb. 23 characins, and catfish Dissection 2 Written Report Draft due Week 7 Protacanthopterygians: pike, Regulation and Excretion Mar. 2 smelt, and salmon Osmoregulation Exercise NEU NOTE: Course schedule moves forward one week for each postponement due to weather

MSC Biology of Fishes at NEAq

Biology of Fishes/Spring 2010 Aquarium Activity/Week 3

A. Introduction

The Chondrichthyes are one of three classes of fish living on the earth today. They are commonly called the “cartilaginous fishes” because their internal skeleton is made of cartilage, a lighter, more flexible, non-ossified form of calcium phosphate (the main constituent of bone). Fossil groups date to more than 450 MYA and include two lineages (subclasses) that diverged about 400 MYA. Today, there are about 1000 species of chondrichthyans. One lineage is composed of the chimaeras or ratfishes; the other of sharks and rays. We will see representatives from both lineages.

NEAq Fishes Location Phylum Chordata Class Chondrichthyes

Subclass Holocephali Order Chimaeriformes Family Chimaeridae Hydrolagus colliei spotted chimaera Cold Marine

Subclass Elasmobranchii

Division Selachii (text: Superorder Galea)

Order Orectolobiformes Family Ginglymostomatidae

Ginglymostoma cirratum nurse shark GOT

Order Lamniformes Family Odontaspidae Carcharias taurus sand tiger shark GOT

Order Carcharhiniformes Family Scyliorhinidae

Atelomycterus marmoratus coral cat shark Tropical Scyliorhinus retifer chain cat shark Cold Marine

Division Batoidea (text: Superorder Squalea)

Order Rajiformes Family Rajidae Dipturus laevis barndoor skate Cold Marine Leucoraja ocellata winter skate Cold Marine Leucoraja erinacea little skate Cold Marine Amblyraja radiata thorny skate Cold Marine Raja eglanteria clearnose skate Cold Marine

Order Myliobatiformes Family Dasyatidae

Dasyatis americana southern stingray GOT Family Potamotrygonidae Potamotrygon motoro ocellated river stingray FW/Temperate

Family Myliobatidae Rhinoptera bonasus cownose ray GOT

Week 3:

B. Classes of Fishes

LampreyChondrichthyesOsteichthyes

3 classes of vertebrates = jawless, cartilaginous, bony

Class Chondrichthyes = “cartilaginous fishes”

Week 3

vertebraeskeleton cartilage

no bone jaws paired fins

Distinguishing

Characters Processes

skeletonfinsfin raysscalesjawsteethheartintestine

•respiration

•regulation

•sensory reception

•reproduction

skeleton

fins

ceratotrichia

fin rays

dermal origin

branching, segmentationno branching, no segmentation

lepidotrichia

epidermal origin

s/b ceratotrichia

text error in 5th edition (p. 257)

bonus point

PLACOID

scales

enamel/dentine

enamel/bone

= teeth

dermal

Figure 2.3

epidermal and dermal

Speedo Fastskin designed by 10x Olympic medalist Gary Hall, Jr

placoid scales

jaws and teeth

tiger shark

Chondrichthyes

jaw

loosely connected

Jaw

teeth

Chondrichthyes

embedded, replaced

serially replaced~30,000 teeth avg./life

modified scales

great white Carcharodon carcharius

tooth height ~ body length

Carcharodon

C. megalodon C. carcharius

megatooth great white

~6 cm~17 cm

1:100 ratio

tooth enamel height (cm)≈ total body length (m)

megatooth sharkMiocene 16 to 1.6 MYA

jaw reconstruction of extinct megatooth shark Carcharadon megalodon

1909 (3x too large) recent SI estimate

Carcharodon megalodonmechanical megatooth “Bruce”Amityville, New England

by Peter Benchley, 1974

heart

pericardium: rigid soft

intestine

Distinguishing

Characters Processes

skeletonfinsfin raysscalesjawsteethheartintestine

•respiration

•regulation

•sensory reception

•reproduction

Respiration

spiracles

eyes

electroreceptorsnares5 gill slits (6, 7)

great white shark

gill arch ~ gill slit

ram ventilation

Regulation: ions

retain nitrogen waste = [seawater]

Osteichthyes Chondrichthyes Birds

Nitrogen waste:

lipid-filled liver

1/3 of body wt90% oil

= buoyancy at any pressure= food reserve

Regulation: buoyancy

Sensory Systems

spiracles

eyes

electroreceptorsnares5 gill slits (6, 7)

photoreception

tapetum lucidum (choroid layer)

color vision

lens muscles

chemoreception

1 drop of blood in Olympic-size poolmost sensitive to proteins

mechanoreception

low frequency sounds

electroreception

Stefano LorenziniItaly, 1678

AC muscleDC wounding

perpendicular forces

sexually dimorphic

male

female

Reproduction

cloaca anal and urogenital opening

myxopterygia

internal fertilization

embryo development

external

internal

nutrient sourcesyolkplacentaeggsembryos

no larval stage

oviparityeggs develop external

~40%

“live”

ovoviviparityeggs develop internal

viviparityyoung develops internal

life history strategy

large size

long life

late maturity

infrequent mating

long gestation

few large young