Chapter 5 Flashcards
what two abilities are hagfish renowned for?
tie themselves in a knot, large amounts of slime
are hagfish highly fercund?
no. very few eggs, no larval phase
what aquatic habitats do lampreys live in?
anadromous/fresh water
which of the two familys of jawless fish are semelparous?
Lampreys
what is the lamprey’s larval stage called?
ammocete
similarities btwn hagfish and lampreys:
- they lack jaws
- they lack gill arches
- single median nostril
- lack paired fins
- lack bone
- cartilaginous internal skeleton
what is the most primitive of all fishes?
hagfish
what are some features that lampreys share with all other vertebrates, and that seperates them from hagfish?
- 2 or 3 semicircular canals
- well developed neural and haemal arches
- true neuromast organs along the lateral line
- extrinsic eye muscles
- nervous regulation of the heart
- capable of hyper osmoregulation
What is the common name for ‘Chondrichthyes’?
cartilaginous fishes
Squatina
Angel sharks
what are morphological characters of the three groups of chondrichthyes?
i) Cartilaginous skeleton
ii) Dermal skeleton of denticles (their scales)
iii) airbladder absent
iv) spiral valve in the intestine
v) internal fertilization (claspers)
vi) osmoregulation by retention of urea
what are the two most diverse groups of sharks?
Carcharhiniformes and Squaliformes
elasmobranchs
sub group of chondrichtheyes, seperating sharks and rays from ratfist
Order Rajiformes, most important morphological features:
i) pec fins are fused to the head over the gill openings
ii) attachment or articulation of the pectoral girdle to the vertebral column
what seperates skates from other rays?
skates are the only rays that lay eggs (OVIPAROUS)
(thought to be sister group of guitar fishes)
- paired electric organs along side of tail
- claw-like spines along lateral extremes of disc
Order Pristiformes: what is the common name?
sawfishes VIVIPAROUS
how are the toothed rostrum different between sawfish and sawshark (family pristidae)?
sawshark have irregular teeth, whereas sawfish are regularly placed teeth on their snout. VIVIPAROUS
Order Torpediniformes: who are they?
torpedo or electric rays, tropical to temperate. Distinguished by huge electric organs along the lateral margin of the disc. stun prey, defend against attack by predators. VIVIPAROUS
Order Rhinobatiformes: who are they?
guitarfishes. VIVIPAROUS, specialized in their gill arches. body ranges from shark-like to ray-like. Benthic
Order Miliobatiformes: who are they?
stingrays, eagle rays, manta rays, cownose.
- most considered specialized for active swimming
- some considered epipelagic
- pec fins firmly attached to spine by ‘ball and socket’ arrangement
Former Order Dasyatiformes: who are they?
stingrays. member of Myliobatiformes. VIVIPAROUS. serrated spine at base of tail
what is a Holocephali?
infraclass of chimeras, relatives to sharks and rays. exist under the order of chondrichthyes.
what defines chimeras from the rest of em?
i) large, permanent, slow growing tooth plates
ii) upper jaw is fused to the cranium
iii) they have only one single gill opening
