Fishy Glub Glub Exam

Fishes

>35,000 extant spp. - >100 jawless spp, ~1,100 cartilaginous spp; 60% marine, 1% brackish, rest FW; higher diversity in tropics

Marine Fish Hot Spot

Indo-Pacific

FW Fish Hot Spot

Continenets

Fish Defining Features

Chordate and Craniate

Chordate

dorsal hollow nerve chord or nodochord; post-anal tail; gill slits or gill pouches

Craniate (clade)

brain case; mostly have vertebrates, paired fins, gills, and ectothermic

Class-level Clades

Myxini, Petromyzontida, Chondrichthyes, Osteichthyes

Myxini Clade

Hagfishes

Petromyzontida Clade

Lampreys

Chondrichthyes Clade

Sharks and Rays

Oesteichthyes Clade

non-tetrapod

When to use the term “fish”

one fish or multiple of the same type of fish

When to use “fishes”

multiple types of different fish

binomial nomenclature

minimum 2-part name; 1st part is genus (always capitilized); 2nd part is the specific epithet and unique for each species (always lowercase and never stands alone)

Major Fish Groups

Classes, Orders (suffix “-iformes”), Families (suffix “-idae”)

Biological Species

reproductively distinct

Evolutionary Species

distinct ancestor → descendant lineage (better than bio spp.)

Clade

complete taxonomic group; stem ancestor + all descendants

Monophyletic (single ancestor) Clade

valid clade

Paraphyletic Clade

incomplete/omission; ancestral lineage but missing some descendants

Polyphyletic Clade

different ancestors; fundamental issue with tree

Character

inherited trait

Plesiomorphy

ancestral (“older”) trait - connects

Apomorphy

derived (“newer”) trait - separate

Synapomorphies

shared apomorphies within 2+ taxa; recent homology

Taxonomic Character Types: Morphological

meristic (countable structures - fin rays, myomeres, vertebrae), morphometric (measurable structures - lengths, ratios), and anatomical (qualitative/descriptive)

Taxonomic Character Types: Physiological

internal/functions

Taxonomic Character Types: Cytological

cell structure

Taxonomic Character Types: Behavioral

must be live so hard to use

Taxonomic Character Types: Biochemical

proteins, RNA, DNA (best); green gene v. red gene

Genetics in Systematics

replaces other methods, complements other methods; super clades (fish)

What are the super clades?

Jawless (Agnatha) and Jawed (Gnathostoma)

Are cartilaginous or bony fish older?

cartilaginous

Voucher Specimen

positively identified for documentation purposes

Physical Fish Collections (dead)

voucher specimen; standardized documentation; long-term preservation; curated at museums, universities, and private collections (largest is Smithsonian, 2nd largest is California Academy of Sciences)

Type Species

clade-level representative (like entire genus or family)

Taxa naming follows the “Principle of Priority”

1st valid name = official one; usually used for family level and below

Categories of Type Specimens

Primary and Secondary

Primary Type Specimen

most valuable

Primary Type Specimen: Holotype

original specimen

Primary Type Specimen: Syntypes

multiple specimens in place of one holotype

Primary Type Specimen: Lectotype

selected representative syntype to proxy for holotype

Primary Type Specimen: Neotype

replacement holotype

Secondary Type Specimen

not holotype and not holotype replacements; supplement to primary type specimens

Secondary Type Specimen: Paratype

additional type-series specimens; came from the same holotype collection

Secondary Type Specimen: Paralectotype

leftover syntypes if a lectotype is selected

Secondary Type Specimen: Topotype

shared locality as the primary type; can source from different collections; most common

Secondary Type Specimen: Allotype

opposite-sexed paratype to the holotype

(DNA) Barcoding

Short mtDNA - G55 bp of cytochrome oxidase subunit 1 gene; globally used for all animals

Osteology

the study of bones

How to (directly) study fish skeletons

Dissections and “Clearing and Straining” Technique

Diessctions

1. Skinning + De-fleshing

2. Dehydrate (ethanol)

3. Processing (dermestids, ants, labor)

4. De-Greasing (ammonia)

5. Whitening (H₂O₂ - optional)

Tools: Knives, scalpels, brushes

“Clearing + Straining” Technique

1. Fix + Preserve - formalin/ethanol (DNA is inert)

2. Cartilage Stain - Alcian blue

3. Bone Stain - Alizarin red S

4. Clearing - trypsin (but keeps collagen)

5. Storage - glycerin

Cranium

braincase + sense organs

upper skull

Neuro-cranium

Chondrocranium

embryonic cartilage origin; ossifies into bone (osteichthyes)

Dermatocranium

dermal bones (scale derived); overlies chondrocranium; lacking in chondrichthyes

Neurocranium spatial regions

1. Ethmoid

2. Orbital

3. Otic

4. Basicranial

Lower Skull

Branchio-cranium (not true cranium)

Branchial Complex

true gill support bones

Fish Gill

1^o lamellae on one gill arch (gill filaments); high surface area

How many gill pairs do most bony fish have?

4

Gills: Ventilation Path (water)

mouth → gills → operculum

Counter-current exchange

1. Deoxygenated blood pumped into lamellae

2. water circulates past lamellae

3. Gas equalization (diffusion)

4. Oxygenate blood exits gill

Requires water flow

Buccal Pumping

pump water from mouth into both opercular chambers; most fishes

Ram Pumping

swim with mouth partially or completely open; sustained swimmers

Hagfish Breathing

Nose breathers - single, central nostril; nostril → velum pumping → gills OR Pharyngeo-Cutaneous Duct (PCD) - left side only, largest opening at end of gills, can blow water out of it OR can breathe through skin

Lamprey Breathing

gill breathers (two-way gill system)

Fish Suck

most fishes suction feed

Old Suck

jawless fish (hagfish, lamprey)

New Suck

most teleosts (modern day bony fish); protrusible jaws (“Gape”)

Gape

maximum mouth opening

Random Suck

various spp. (rays, eels); non-protrusible jaws (bowfin); pharyngeal jaws

Pharyngeal Jaws

work as inner jaws; movable with muscles; bony fishes only; best developed where don’t suck (morays) and need to chew more (parrotfish) and also cichlids for some reason; upper jaw = modified upper pharyngeal tooth plates (from arches #1-4); lower jaw = modified #5 gill arch

Teeth: Elongate

for stabbing, holding; usually recurved (e.g anglerfish)

Teeth: Villiform

small, needle-like; stabbing, holding (for smaller prey)

Teeth: Triangular

not grabbing prey but taking chunks out; slashing

Teeth: Caniniform

conical pointed; curved or straight; piercing, holding (higher bite force)

Teeth: Cardiform

short, fine-pointed; densely packed into; brush-like rows; holding

Teeth: Molariform

thick, flattened; crushing, grinding

Teeth: Incisors

laterally flattened; often fused into beak; cutting

Mouth Position: Terminal

most fishes; pointy-end forward

Mouth Position: Superior

least common; upward feeding

Mouth Position: Sub-terminal (inferior)

sucking-shaped mouth

Notochord

ancestral chordate feature - muscle attachment (for swimming); mostly cartilage - hagfishes (ancestral) and extant lobe-fins (derived)

Vertebral Column (vertebrae)

wraps around notochord + replaces it; bone or cartilage; all other fishes (mostly)

Myomere

Fish body segment

Mono-spondylous

1 vertebra per myomere

diplo-spondylous

2 vertebra per myomere; lots of sharks, more body flexibility; elasmobranch, lungfish, bowfin tails

Pleural Ribs

“ventral ribs”; protect “viscera”; left + right pairs; attached to (vertebral) parapophyses

Urostyle

last vertebra; (often) elongate

Caudal Fin Shape: Proto-Cercal

unspecialized, ancestral shape; lancelets, agnathans, gnathostome larvae

Caudal Fin Shape: Hetero-Cercal

unequal-lobed; vertebrae extends into upper (or lower) fin lobe; Chrondrichthyes, primative bony fishes (sturgeons, gars)

Caudal Fin Shape: Homo-Cercal

equal-lobed; most bony fishes

Caudal Fin Shape: Lepto-Cercal

2^o derived protocercal shape; lobe-fins, rattails; various eels

Pectoral Girdle on Elasmobranchs

Sharks - Coraco-scapular cartilage

Rays - wraps around head

Pelvic Girdle on Elasmobranchs

ischio-pubic cartilage

Pectoral and Pelvic Girdles

Supports for paired fins; missing in jawless fishes; fish appendiculars not attached to vertebrae

Dorsal Myomeres

Ep-Axial Mass

Center of Myomeres

Horizontal Septum