Lecture 11: Early Teleosts

• Teleostei is noted for their increased maneuverability and functionality due to independence of their tail from their body. This is due to their development and use of multiple muscles including...

  • Flexor Ventralis
  • Hypochordal longitudinalis
  • Interradial muscles
  • Flexor dorsalis
  • Supracarinalis
  • Infracarinalis
• What group on this cladogram lacks dedicated caudal muscles?

  Bichir (polypterus)

  
• What group on this cladogram first evolved a Flexor Ventralis?

  Gar (Lepisosteus)

  
• What group on this cladogram first start evolving more complex tail muscles such as Hypochordal longitudinalis, Interradial muscles, and a supracarinalis for movement?

  Amia

  
• What muscles did the group Amia start evolving in conjunction with greater tail movement?

  Hypochordal longitudinalis

  Interradial muscles

  Flexor dorsalis

  Supracarinalis

  Infracarinalis

  
• What muscles did the teleosts have in conjunction with greater tail movement that amia didn't?

  Infracarinalis

  
• What group on this cladogram has the most tail maneuverability and functionality?

  Teleostei

  
• Teleosts are noted for having likely evolved from genome duplication, something very notable because as long as they have one functional copy the other can mutate and further spur evolution on without serious deleterious effects thus allowing for greater evolutionary possibilities
• Teleosts make up 96% of all extant fish species
• Moon eyes belong to what order and family?

  Hiodontiformes

  • Hiodontidae
• What families belong to the group Osteoglossiformes?

  Osteoglossidae (Arowanas)

  Notopteridae (Old world knife fishes)

  Mormyridae (Elephantfishes)

  Gymnarchidae (Aba)
• What is notable about the family Osteoglossidae?

  Arowanas

  Live in tropical fresh water

  Long bodies

  Large scales of many colors

  Elongate dorsal and anal fins

  The largest Arapaima is the Arapaima gigas

  Grows to 4.5 m

  
• What is notable about the family Mormyridae?

  Elephant fishes

  Live in fresh water

  All species in Africa

  Trunk-like appendage on snout or chin

  Electric organs (tuberus receptors) to detect prey

  • Modified muscle in caudal peduncle

  Use electrical signals for communication

  • Very sophisticated use. Though each individual has a unique signal and they are used to establish dominance hierarchies

  
• What is notable about the superorder Elopomorpha?

  Extremely diverse morphologically

  Includes tarpons, bonefish, eels

  All have a leptocephalus larval stage (appearance is species dependent)

  Can stay leptocephalus for a very long time

  
• What member of elopomorpha will this leptocephalus larvae turn into?

  Tarpon

  Lady Fish

  
• What member of elopomorpha will this leptocephalus larvae turn into?

  Notocanthan

  Bonefish

  
• What member of elopomorpha will this leptocephalus larvae turn into?

  Eels

  Gulpers

  
• What is notable about the order Elopiformes?

  Tarpon and relatives

  2 families

  • Elopidae (ladyfish)
  • Megalopidae (tarpons)

  Streamlined predators

  Cycloid scales

  Forked tails

  Tropical/sub-tropical habitats

  Shallow marine habitats (near shore)

  Occasionally found in brackish water

  Larvae are larger than juveniles

  Fork-tailed type larvae
• What is notable about the order Albuliformes?

  Bonefish, Spiny eels, Halosaurs

  3 families

  • Notacanthidae (Spiny eels)
  • Halosauridae (Halosaurs)
  • Albulidae (Bonefishes)

  Sensory canal on mandible is in open groove (other elopomorphs have it in closed canal)

  Leptocephalus larvae (up to 6 feet)

  • Filament-tailed type

  Differ from true eels because albuliformes have pelvic and pectoral fins

  Flexible jaws

  
• What is notable about the order Anguilliformes?

  True eels

  Leptocephalus larvae

  • Round-tailed type
  • Species or genus specific

  Very elongate bodies

  Lack pelvic fins (often pectorals too)

  Median fins continuous with caudal fin

  Cycloid scales deeply embedded or absent

  No gill rakers

  Reduced skeleton (mostly vertebral elements)

  Jaw inflexible

  • Why they often have elaborate pharyngeal jaws

  
• What are the major groups of the Anguilliformes?

  Angullidae (Freshwater eels)

  Muraenidae (Moray eels)

  Congridae (Conger eels)

  Ophichthidae (Snake eels)
• What is notable about the major eel group Angullidae?

  Freshwater Eels

  Catadromous

  • Migrate to spawn
  • Mature in freshwater
  • Spawn at sea
  • Larvae migrate back to freshwater
  • Negatively effected by dams

  Large pectoral fins

  American eels exclusively spawn in Sargaso Sea

  Larvae grow in fresh water

  
• What is notable about the major eel group Muraenidae?

  Moray eels

  No scales

  No paired fins

  Jaws with recurved teeth

  Mobile pharyngeal jaws for prey capture

  Nape region elevated

  Posterior nostril high and above/before the eye

  
• What is notable about the major eel group Congridae?

  Conger eels

  Small Palatal teeth (teeth on the midline of roof of mouth)

  Teeth not canine-like

  Lower jaw about as wide as upper jaw

  Have pectoral fins

  Includes garden eels

  Varying sizes (larger and smaller eels)

  
• What is notable about the major eel family Ophichthidae?

  Snake and worm eels

  May or may not have paired fins

  Usually no caudal fin

  Excurrent nostrils on lip or in mouth (never outside this area)

  • Usually covered by a small flap or in a short tube

  Finless spike-like tail for burrowing

  Burrow in soft bottoms

  • Most burrow tail first
  • Those that do not burrow tail first have reinforced skulls for burrowing

  
• What is notable about the order Saccopharyngiformes?

  Gulpers

  Not true eels

  • Sister group to eels

  Large mouth attached to sack-like body. The body expands around food

  Highly anatomically modified

  • Neuromasts on stalks away from the body to increase sensitivity
  • Anatomically modified vertebrae
  • Light organ on tail used to lure prey

  Lack the following due to buoyancy reasons:

  • Opercular bones
  • Branchiostegals
  • Maxilla
  • Premaxilla
  • Volmer
  • Parasphenoid
  • Scales
  • Paired fins
  • Ribs
  • Swim Bladder

  
• What is notable about the superorder Ostarioclupeimorpha?

  Also called Otocephala

  Includes herrings and minnows

  • Sister relationship between herrings and minnows supported by morphological and genetic data

  Clupeomorphs have some features of the Weberian apparatus (not the actual apparatus) which is the defining character for the Otophyseans

  
• What are notable features of the order Clupeiformes?

  Includes herrings, shad, sardines, menhaden, and anchovies

  Have a unique otophysic connection between ear and swim bladder

  • Sensitive to the sound range made by marine mammals
  • Likely evolved for predator avoidance

  Clupeiformes do not have a Weberian apparatus

  Schooling planktivores

  Most important forage fishes for large piscivores in the upper water column

  Adapted to live in well-lit costal surface waters

  • Large eyes

  Use mirror camouflage

  Compressed body form

  Silvery color

  Flexible Mouths

  Fine Gill Rakers

  
• What are the noted characters of Clupeiformes and why they developed?

  Silvery color

  • created by Guanine crystals
  • Reduces visibility to predators

  Laterally compressed body form

  • NEVER wide
  • Reduces visibility to predators

  Flexible mouth

  • Adapted for plankton feeding

  Fine Gill Rakers

  • Adapted for plankton feeding

  
• What is notable about Mirror Camouflage used by Clupeiformes?

  Guanine crystals in the skin create a silvery colour

  Guanine crystals reflect light at about the same wavelength of down-welling light

  Angle of guanine crystals determines the direction of light reflection

  Fishes reflect the surrounding water light levels

  Works as effective camouflage from a distance
• What are the 2 major families of clupeiformes?

  Clupeidae

  • Herrings
  • Small mouth that ends in front of eye

  Engraulidae

  • Anchovies
  • Large mouth that extends past the eye
• What is notable about the family Clupeidae?

  Herring, shad, sardines, menhaden

  Characters

  • Keeled bellies (scaled ridge that runs along the belly)
  • Silvery
  • Cephalic lateral line canals prominent on the head
  • Body lateral line canals absent
  • Tight schoolers so neuromasts here wouldnt be beneficial
  • Mouth usually terminal
  • Mouth small
  • Usually no teeth or small teeth
  • 5 to 10 branchiostegal rays

  
• What are some defining characteristics of Menhaden?

  Deep V in upper lip

  Deeper body (Oval shape)

  Series of smaller spots behind the main humeral spot

  
• What are some defining characteristics of Shad?

  Shallow V in upper lip

  Shallower body (rounded but shallow)

  Gizard Shad and Threadfin Shad have humeral spot but often lack smaller spots

  
• What are some defining characteristics of Herring?

  Shallow V in upper lip

  Shallower body (WAY shallower)

  Pretty elongate

  Often have humeral spot

  Rarely have other spots than humeral spot

  Mouth small

  Maxilla does not extend beyond eye

  Ventral midline of belly usually with scutes

  
• What is notable about migratory Clupeids?

  Anadromous species need connections between rivers and the sea or rivers and lakes

  Dams have cut off traditional migration routes

  • Often causes mortality prior to spawning via deoxygenation
  • Fish ladders help but not all dams have these
• What is notable about Freshwater Clupeids?

  North America - Gizzard Shad

  Forage fish for game species

  Often introduced and outcompete game fish

  Contribute to eutrophication from feces

  
• What is notable about Engraulidae?

  Anchovies

  Characters

  • Overhanging snout (may be slight or obvious)
  • Mouth inferior (Under snout)
  • Long upper jaw ventral of the eye (Tilted towards bottom)
  • 7 to 19 branchiostegal rays
  • Pelvic fins 7 to 10 rays
  • Small (less than 15 cm) with elongate body
  • Translucent often with silver stripe

  DO NOT CONFUSE THESE WITH SILVERSIDES LOOK AT THE MOUTH

  
• How do climate forces drive populations?

  Anchoveta and other clupeiforms populations are strongly driven by large climatic forces

  Abundance is dependent on El Nino and La Nina

  • The stronger the El Nino the worse the population crash
• Why does El Nino negatively effect Anchoveta and clupeiforms?

  Anchoveta spawn in the spring when plankton are abundant from nutrients upwelling

  El Nino suppresses nutrient upwelling and reduces plankton populations