Pleuronectiformes!

By: Steve Mussmann

and Christine Knight

Where it’s at…

Monophyletic group 11 families

Pleuronectiformes

Bilaterally symmetrical as larvae Eye migrates and asymmetrical as adult Adults lack swim bladder Mostly marine… only a few freshwater species Compressed body Benthic fishes Eat benthic invertebrates and fish

All the families…

11 familiesAchiridae- American SolesAchiropsettidae- Southern FloundersBothidae- Lefteye FloundersCitharidae- CitharidsCynoglossidae- TonguefishesParalichthyidae- Large Tooth FloundersPleuronectidae- Righteye FloundersPsettodidae- PsettodidsSamaridae- Crested FloundersScophthalmidae- TurbotsSoleidae- Soles

Achiridae- American Soles

33 species Eyed-side lower lip

has fleshy rim Occur in fresh,

brackish, and marine habitats

Achiropsettidae- Southern Flounders 6 species Only marine

habitats Antarctic and

Sub-Antarctic waters

Eyes on left side Pectoral fins tiny

or absent

Bothidae- Lefteye Flounders

162 species Only marine Temperate and

tropical---Atlantic, Indian, and Pacific Oceans

Eyes on left No spines in fins Anus on blind side

Citharidae- Citharids

7 species Only marine Mediterranean,

Indian, and Japan to Australia

Eyes either side Short pelvic fins Anus on eyed

side

Cynoglossidae- Tonguefishes 140 species Fresh, brackish, and

marine habitats Tropical and sub-

tropical Eyes small and on

left side Asymmetrical mouth No pectoral fins Commercially

important

Paralichthyidae- Large-tooth Flounders 116 species Fresh, brackish,

and marine habitats Atlantic, Indian, and

Pacific Oceans Eyes on left side No spines in pelvic

and pectoral fins

Pleuronectidae- Righteye Flounders 102 species Fresh, brackish and

marine habitats---mostly marine

Arctic, Atlantic, Indian, and Pacific oceans

Eyes on right side Camouflage Fins have no spines Commercially

important

http://www.youtube.com/watch?v=ty9f5_pxMas

Psettodidae- Psettodids

3 species Marine only Most primitive

Few vertebrae Swim upright

Eyes on either side

Samaridae- Crested Flounders 21 species Marine only Indo-pacific---

tropical and sub-tropical waters

Deep waters Postcleithrum

absent

Scophthalmidae- Turbots

9 species Brackish and marine

waters North Atlantic, Baltic,

Mediterranean, Black seas

Eyes on left side Large mouth---

prominent jaw

Soleidae- Soles

163 species Fresh, brackish, and

marine habitats Europe to Australia

and Japan Eyes on right side No fin spines Commercially

important

Evolution of Asymmetry

Born with eyes on both sides of head

Gradually migrates so eyes on same side of head

Adults are asymmetrical

http://www.youtube.com/watch?v=bldN-lbyqsE

Matt Friedman 2008

Evolution of asymmetry gradual or in one large jump?

Discovered transitional fossil that has asymmetrical skull eyes on both sides of the head!

Find the Flounder?!

Chromatophore Pigment

containing Light reflecting

http://www.youtube.com/watch?v=GAZSg2tqe7k

Experiment!

Winter Flounder

Conservation… IUCN lists Atlantic Halibut as

endangered and the Yellowtail Flounder as vulnerable

Overfishing Late age of sexual maturity Looking for alternative

species to fish

Review Questions!

Name three traits shared by the Pleuronectiformes. What is unique about the Southern Flounders? In what family is camouflage most common? What are the advantages of camouflage for

Pleuronectiformes? Make an argument for the gradual evolution of

asymmetry in Pleuronectiformes. Describe the development of a flatfish. What are some reasons for the endangered status

of the Atlantic Halibut?