What are the four common measurements of length? What must be done when measuring length?
FORK LENGTH (FL): TIP OF SNOUT to TAIL FORK
TOTAL LENGTH, (TL): SNOUT TIP to END OF COMPRESSED TAIL; = maximum length of fish
STANDARD LENGTH (SL): tip of snout to posteriror end of HYPURAL PLATE; most often used in systematic studies -- accurate and comparable but difficult to do
POST-ORBITAL-HYPURAL LENGTH (POH): back of ORBIT to end of HYPURAL PLATE; used for mature Pacific salmon to control for effects of sexual dimorphism and tail damage. One must always indicate the measure which is being referred to and the units used when providing any fish length measures
What is the hypural plate and how does one find it?
The hypural plate is a series of separate (primitive state) or fused (derived state) bones that connect to the last few vertebra (primtive state) or a single specialized vertebra (UROSTYLE in derived state).
Supports the caudal fin rays
To find the end of the hypural plate on a whole fish, bend the caudal fin towards you and observe the resulting "crease" in skin at the end of the caudal peduncle.
How do true spines differ from soft rays?
TRUE SPINES: - usually hard and pointed - unsegmented - unbranched - solid
SOFT RAYS: - usually soft and not pointed - segmented - usually branced - bilateral, with left and right halves
Which fins are true spines usually found? Are there any exceptions?
exceptions exist in Siluriformes (catfishes) where soft rays are fused on pectoral fins to create spines.
List the types of scale from primitive (Chondrichthyes) to derived fish (Actinoptyergii).
Placoid scales (Sharks)
Ganoid scales (Gars)
Leptoid scales a. cycloid (primitive teleosts, salmon) b. ctenoid (derived teleosts, rockfish)
What are ganoid scales?
Found in most primitive members of Actinoptyerigians, made up of a hard, thick ganoine (enamel-like inorganic bone salt excreted by the dermis) covered scale that forms a heavy DERMAL ARMOUR.
Usually rhomboid in shape and have articulating peg and socket joints between them.
Describe leptoid scales and the types of leptoid scales that occur.
Reduced and having lost the ganoine layer, leptoid scales are found in teleosts as CYCLOID SCALES usually in PRIMITIVE teleosts and CTENOID scales in more derived teleosts.
Leptoid scales -- either types -- can be modified to form bony scutes also.
What are the differences between ctenoid and cycloid scales?
Ctenoid scales have teeth-like projections along the backside (posterior).
Cycloid scales have a smooth edge on the posterior side.
What are the primitive and derived states of 1) scales; 2) spines; 3) fin positions; and 4) presence of protrusible jaws found in teleosts?
- Scales are cycloid
- Fins lack true spines
- Pelvic and pectoral fins lie ventrally, with pelvic fins lying posteriorly along body and pectorals anteriorly
- No protrusible jaws: pre-maxilla only slightly flexible
- Ctenoid scales exist
- True spines are found on the dorsal, pelvic, and anal fins
- Pectoral fins lie behind operculum/are more dorsally located, and pelvic fins are found anteriorly, below pectorals but remain ventral
- Protrusible jaw exists as pre-maxilla becomes more flexible and makes up most of the upper jaw
What are meristic counts? Examples? What are the standards for completing meristic counts?
Meristic counts are those done on serially repeated structures.
Examples include vertebral counts, fin-ray counts, and gill-raker counts, which are important for species identification and population/stock identification within species.
Standards for meristic counts:
- all measurements are done on the left side as the standard side
- true spines designated by Roman numerals, and soft rays by Arabic numbers, and all spines are counted regardless of size but soft ray counts do not include the first anterior rays that are less than half the height of the longest ray. The last two rays are counted as only one.
- Gill rakers counts include all rudiments i.e. small bumps that occur at the end of the obvious gill rakers.
What bones are found in the lower jaw of teleosts? What bones are found in the upper jaw?
Lower jaw are made up of: - the dentary - the angular - basihyal/glossohyal bone of the lower palate
Upper jaw bones: - pre-maxilla - maxilla - palatine - vomer
What are the bones found in Teleost neurocranium?
Frontal Supraoccipital Parietal Orbitosphenoid Parasphenoid Vomer
What are the bones found in the 1) jaws, 2) suspensorium, and 3)opercular apparatus of teleosts?
JAWS: dentary, angular, basihyal, premaxilla, maxilla, palatine, and vomer
SUSPENSORIUM: hyomandibular, metapterygoid, endopterygoid, ectoptyerygoid, and quadrate.
OPERCULAR APPARATUS: angular, preopercle, interopercle, opercle, subopercle
What bones make up the hyoid apparatus and what is its function?
Hyoid apparatus serves as a base for connection of the four complete gill arches to the hypohyal and glossohyal, but also functions in buccal cavity expansion during feeding and respiration
- Basihyal/glossohyal Hypohyal
- Urohyal is connected ventrally to hypohyal
- Interhyal is on top of epihyal
What is the pectoral girdles form and function?
Includes the cleithra which supports the pectoral fins, where the epaxial and hypaxial musculature are connected to the rest of the hyoid apparatus and the skull.
It makes up the hard back, inside end of the gill cavity.
Explain hyoid coupling in terms of which muscles pull on which bones. What is the end result of this series of muscle contraction?
Epaxial musculature pulls on rear of cranium and causes head to rotate upward relative to the body axis.
Hypaxial musculature pulls on the cleithrum.
The cleithrum translates this contractions through the STERNOHYOIDEOUS to the HYOID APPARATUS.
The hyoid apparatus then pulls on the PROTRACTOR HYOIDEOUS muscle that is connected to the lower dentary jaw.
This INDIRECT way of opening the mouth results in EXPANSION of the ORAL cavity, creating SUCTION and water is drawn into the mouth as the lower jaw is depressed.
What is involved in the opercular coupling of the mouth?
The LEVATOR OPERCULI muscle that orginates on the craniuma nd inserts along the dorsal margin of the opercle contracts and causes OPERCLE to swing UP and BACKWARD.
The SUBOPERCLE and INTEROPERCLE are attached to the opercle and movement is transmitted throughout all the elements of the OPERCULAR APPARATUS, causing the INTEROPERCLE to pull back on the lower jaw by means of a strong ligament that lies between the bones -- INTER-ARTICULAR LIGAMENT.
This is an DIRECT mechanism for opening the mouth that does not involve the creation of suction.
What is the adductor mandibulae and its function? What is its relation to closing a teleost's mouth?
Adductor mandibulae are large complex muscles i.e. CHEEK MUSCLES divided into three or four separate sections, and originates on bones of the suspensorium and is inserted along the length of the PRIMORDIAL LIGAMENT (or maxillo-mandibular ligament).
The adductor mandibulae is related to all movement to feeding as well as respiration.
The adductor mandibulae muscles pull on the primordial ligament causing the upper jaw to pull back up and in.
What is the class, and infraclass of bony fishes?
What are the characteristic traits of Actinopterygians branchial structure?
There is a single gill -- OPERCULAR -- cover (vs separate gill slits in Chondrichthyes), and a greater SEPARATION of the individual gill filaments from the SEPTUM that connects each half of the gill filaments to a GILL ARCH.
Spiracle is no longer present, except for in some primitive sturgeons.
What is a hemibranch (demibranch) and what is a holobranch?
HEMIBRANCH is one half of the paired filaments and the whole paired filament is a HOLOBRANCH.
What is the difference between primitive and derived Actinopterygians in terms of swim bladder?
Primitive swim bladders are PHYSOSTOMOUS meaning the swim bladder is connected to the oesophagus by the PNEUMATIC DUCT. There is also no RETE MIRABILE.
In Derived Actinoptyerigians, swim bladders are PHYSOCLISTOUS meaning it is closed off and gas exchange occurs through diffusion via blood in the RETE MIRABILE.
Describe the Actinopterygian heart structure, from blood flow coming from the body into the gills.
What is the difference between a Chondrichthyes heart and that of an Actinopterygians?
Actinopterygians have a BULBUS ARTERIOSUS which contains no valves.
Chondrichthyes have a CONUS ARTERIOSUS.
Both are primarily elastic, and work to reduce the pulsed nature of the blood leaving the ventricle giving it a more even constant flow.
What separates the two epaxial musculatures? What separates the hypaxial and epaxial musculatures?
The VERTICAL SEPTUM separates the two epaxial musculature.
The HORIZONTAL SEPTUM separates the epaxial from the hypaxial musculatures.
What are the small muscle bundles found on the most dorsal and ventral muscle bundles?
Dorsally = SUPRACARINALIS Ventrally = INFRACARINALIS
Describe the different components of a single vertebra.
The upper spine is the NEURAL SPINE which is connected to the CENTRUM by the NEURAL ARCH.
The ventral part of the vertebra consists of the HAEMAL SPINE that is connected to the CENTRUM by the HAEMAL ARCH.
What are the bonese that connet the dorsal rays to the dorsal musculature?
What connects the caudal fin to the vertebrae in primitive Actinopterygians and derived Actinopterygians?
Primitive actinopterygians have a HYPURAL that is unfused and connected to branching vertebrae to the caudal fin via the UROSTYLE. The hypural plates are more numerous and the majority originate from the ventral part of the last few vertebrae.
In derived Actinopterygians, the caudal fin is connected to the vertebrae via the hypural by fused vertebrae -- the UROSTYLE. The hypural plates are fused together and they are symmetric from top to bottom.
What are the 7 caudal fin types?