Superorder Squalomorphi – squalomorph sharks
Spelling:
Squalomorphi. S,Q,U,A,L,O,M,O,R,P,H,I. Squalomorphi.
Taxonomic Rank: Superorder
Key Characteristics: Often deep-sea or cold-water species, smaller body size, reduced spiracle, lack of anal fin
Biological Context: Includes dogfish and six-gill sharks. Adapted for low-light, high-pressure environments. Represent a more primitive lineage than galeomorphs, with slower metabolism and specialized sensory systems.
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Order Hexanchiformes – six- and seven-gill sharks
Spelling:
Hexanchiformes. H,E,X,A,N,C,H,I,F,O,R,M,E,S. Hexanchiformes.
Taxonomic Rank: Order
Key Characteristics: More than five gill slits, single dorsal fin, large spiracle, soft-bodied
Biological Context: Deep-sea and cold-water specialists. Retain ancestral traits such as multiple gill openings and simple jaw suspension. Important for understanding early shark evolution.
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Order Squaliformes – dogfish sharks
Spelling:
Squaliformes. S,Q,U,A,L,I,F,O,R,M,E,S. Squaliformes.
Taxonomic Rank: Order
Key Characteristics: Small size, spiny dorsal fins, no anal fin, deep-water distribution
Biological Context: Includes many species adapted to mesopelagic and bathypelagic zones. Often slow-growing and long-lived. Economically important but vulnerable to overfishing due to low reproductive rates.
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Family Squalidae – dogfish sharks
Spelling:
Squalidae. S,Q,U,A,L,I,D,A,E. Squalidae
Taxonomic Rank: Family
Key Characteristics: Slender body, large eyes, dorsal fin spines, ovoviviparous reproduction
Biological Context: Includes spiny dogfish and relatives. Found in temperate and deep-sea habitats. Known for long gestation periods and high resilience to cold environments.
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Division Batomorpha – rays
Spelling:
Batomorpha. B,A,T,O,M,O,R,P,H,A. Batomorpha.
Taxonomic Rank: Division
Key Characteristics: Flattened body, enlarged pectoral fins fused to head, ventral gill slits, reduced or absent dorsal fin
Biological Context: Includes skates, stingrays, electric rays, and sawfishes. Adapted for benthic life with specialized feeding and locomotion. Electroreception and venom are common in many species.
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Order Torpediniformes – electric rays
Spelling:
Torpediniformes. T,O,R,P,E,D,I,N,I,F,O,R,M,E,S. Torpediniformes.
Taxonomic Rank: Order
Key Characteristics: Rounded body, electric organs, slow swimmers
Biological Context: Use electric discharge for defense and prey capture. Found in shallow coastal and deep benthic zones. Represent a unique sensory and predatory strategy among elasmobranchs.
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Order Rajiformes – skates
Spelling:
Rajiformes. R,A,J,I,F,O,R,M,E,S. Rajiformes.
Taxonomic Rank: Order
Key Characteristics: Thick tails, dorsal fins present, oviparous reproduction with egg cases
Biological Context: Common in temperate and deep-sea environments. Lay "mermaid's purses." Important for benthic food webs and evolutionary comparisons with stingrays.
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Order Pristiformes – sawfishes and guitarfishes
Spelling:
Pristiformes. P,R,I,S,T,I,F,O,R,M,E,S. Pristiformes.
Taxonomic Rank: Order
Key Characteristics: Elongated rostrum with teeth (sawfishes), body intermediate between sharks and rays
Biological Context: Sawfishes are critically endangered due to habitat loss and bycatch. Their rostrum is used for prey detection and manipulation. Guitarfishes show transitional morphology between sharks and rays.
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Order Myliobatiformes – stingrays and mantas
Spelling:
Myliobatiformes. M,Y,L,I,O,B,A,T,I,F,O,R,M,E,S. Myliobatiformes.
Taxonomic Rank: Order
Key Characteristics: Disc-shaped body, venomous tail spine (in stingrays), filter feeding (in mantas)
Biological Context: Stingrays are benthic predators; mantas are large pelagic filter feeders. Exhibit complex social behavior and long-distance migrations. Important for reef and open-ocean ecosystems.
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Subclass Holocephali – ratfishes and chimeras
Spelling:
Holocephali. H,O,L,O,C,E,P,H,A,L,I. Holocephali.
Taxonomic Rank: Subclass
Key Characteristics: Single gill opening covered by operculum, tooth plates instead of individual teeth, long tapering tail, cartilaginous skeleton
Biological Context: Deep-sea specialists and the sister group to Elasmobranchii. Exhibit internal fertilization and unique cranial morphology. Retain primitive traits while showing specialized adaptations for benthic and deep-water habitats.