A Guide to Frequently Used Characters, Character States and Measures
Last updated: 11/27/02
Frequently cited anatomical characters, structures, organ systems, measures and ratios employed in descriptions of cirrate and incirrate octopods are depicted in figures 1-6:
ACRONYM DEFINITIONS AND DERIVATIVES
One possible way of defining the size of an octopus, to standardise peoples reference when dealing with size, would be in accordance with the following:
1 Differs in whole arm sucker counts instead of half arm sucker counts.
2 Differs in not employing mantle width.
3 Differs by dividing fin length measures by mantle length as opposed to head width; head width in species of Opisthoteuthis is somewhat indefinable owing to the anterior-posterior compression of the cephalopedal mass.
4 Differs by excluding the terminal lamellae from inner and outer demibranch lamella counts.
5 Differs in head length being indefinable in many instances in octopods.
Last updated: 11/27/02
Frequently cited anatomical characters, structures, organ systems, measures and ratios employed in descriptions of cirrate and incirrate octopods are depicted in figures 1-6:
ACRONYM DEFINITIONS AND DERIVATIVES
AF | Arm Formula: comparative length of arms expressed numerically in decreasing order (see AL): arm 1 (dorsal), 2 (dorso-lateral), 3 (ventro-lateral), 4 (ventral); e.g. 1.3.4.2., 2.3=4.1. |
AL | Arm Length - arm length measured from beak to tip of arm. ALI, Arm Length Index - AL as a percentage of ML. ALI1-4, Arm Length Index arms 1 to 4 - range of arm length indices, longest to shortest. |
AS | Arm Sucker diameter - diameter of arm suckers (e = enlarged, n= normal). ASIe, Arm Sucker Index (enlarged) - diameter of largest enlarged arm sucker on each designated arm as a percentage of ML. ASIn, Arm Sucker Index (normal) - diameter of largest normal arm sucker (not enlarged) on each designated arm as a percentage of ML. ASIn1-4, Arm Sucker Index (normal) 1 to 4R/L - range of ASIn values arms 1 to 4 R or L. |
ASC | Arm Sucker Count - number of suckers along each entire intact designated arm (to arm tip)1, e.g. ASC2R, total arm sucker count arm 2 right. ASC1-4, Arm Sucker Count 1 to 4R/L (ex. 3R or L male hectocotylised arm, see ASC 3R or L) - range of arm sucker counts excluding counts on hectocotylised arm of male 3R or L. ASC3R (or 3L), Hectocotylised Arm Sucker Count - number of suckers along entire arm (to calamus). |
CaL | Calamus Length - measured from last (distal-most) sucker to calamus distal tip. CaLI, Calamus Length Index - calamus length (CaL) as a percentage of ligula length (LL). |
CiL | Cirrus Length - length of longest cirrus on each arm. CiLI, Cirrus Length Index, CiL as a percentage of the diameter of the largest normal sucker (or mantle length2, whichever designated). |
EO | Eye Orifice diameter - diameter of the opening of eye. |
FL | Fin Length - measured along axis of fin. FL In, Fin Length Inner, greatest length along anterior margin of fin measured in straight line. FL Out, Fin Length Outer, greatest length along posterior margin of fin measured in straight line. FLI In3, Fin Length Index Inner, FL In as a percentage of ML. FLI Out, Fin Length Index Outer, FL Out as a percentage of ML. |
FuL | Funnel Length - the length of the funnel from the anterior opening to the posterior border measured along the ventral midline. FuLI, Funnel Length Index - FuL as a percentage of ML. |
FW | Fin Width (CIRRATES only) - greatest width across one fin perpendicular to axis of fin. FWI, Fin Width Index, FW as a percentage of fin length. |
GiLC | Gill Lamellae Count - number of lamellae on inner and outer demibranchs excluding4 the terminal lamella(e), e.g. 7 outer, 7 inner. |
HdL | Head Length - diameter of orbits along antero-posterior axis of body5. HdLI, Head Length Index -HdL as a percentage of ML. |
HdW | Head Width - greatest width of head at level of eyes. HdWI, Head Width Index - HdW as a percentage of ML. |
LL | Ligula Length - measured from distal-most sucker to tip of arm. LLI, Ligula Length Index - LL as a percentage of hectocotylised arm length. |
ML | Mantle Length - measured from midpoint between eyes to posterior end of mantle. |
MW | Mantle Width - greatest straight-line (dorsal) width of mantle. MWI, Mantle Width Index - MW as a percentage of ML. |
OAI | Opposite Arm Length Index - length of hectocotylised arm as a percentage of its fellow arm on opposite side. |
PA | Pallial Aperture extent - the measurement between the points of attachment of the mantle to the head along the ventral margin of the mantle. PAI, Pallial Aperture Index - PA as a percentage of ML. |
TL | Total Length - measured from end of longest arm to posterior end of mantle. |
WD | Web Depth - measurement of deepest web sector from beaks to to midpoint of sector (Web sector A, dorsal to dorsal arm; B, dorsal to dorso-lateral arm; C, dorso-lateral to ventro-lateral arm; D, ventro-lateral to ventral arm; E, ventral to ventral arm). WDIA-E, web depth range sectors A-E. |
WF | Web Formula - comparative depth of each web sector expressed alphabetically in decreasing order (see WD). WFR/L, right and left web formulas. |
One possible way of defining the size of an octopus, to standardise peoples reference when dealing with size, would be in accordance with the following:
Size | TL (mm) |
Small | <200 |
Small to moderate | 200-300 |
Moderate | 300-500 |
Moderate to large | 500-600 |
Large | 600-1000 |
Massive | >1000 |
2 Differs in not employing mantle width.
3 Differs by dividing fin length measures by mantle length as opposed to head width; head width in species of Opisthoteuthis is somewhat indefinable owing to the anterior-posterior compression of the cephalopedal mass.
4 Differs by excluding the terminal lamellae from inner and outer demibranch lamella counts.
5 Differs in head length being indefinable in many instances in octopods.
- Original publish date
- Nov 27, 2002