Key to identification : Crabs

Key to families:

1. Last legs usually flattened and more or less distinctly adapted for swimming. Usually a small lobe at inner angle of endopodite of first maxillipeds ................................................................................................... Portunidae
2. Last legs not flattened for swimming ............................................................... other families

Key to genera of Portunidae:

1. Bearing more than 7 anterolateral teeth
   1. Surface of carapace smooth and regions indistinct. Manus of chelipeds smoomth and inflated ................................................................................................................. Scylla (Scylla serrata)
   2. Surface of cearpace with regions distinguished. Manus of chelipeds not inflated, usually with granules or ridges.
      1. Carapace narrow, slightly broder than long ................................................other genera
      2. Carapce broad, much broader than long. Anterolateral teeth not alternately large and small; last one much larger than the others ............................................................................................................. Portunus
2. Bearing 7, or less than 7 anterolateral teeth.
   1. Merus distinctly longer than breadth of carapace .............................................. other genera
   2. Merus shorter than breadth of carpace
      1. Anterolateral margin arched and cut into 6 to 7 teeth. Tips of chelipeds pointed ............................................................................................................. Charybdis
      2. Anterolateral margin arched and cut into 5 or less teeth. Tips of chelipeds not pointed ............................................................................................................. other genera

Key to the species of Portunus:

1. Carapace marked with transverse ridges, covered with uniformly distributed granueles.
   1. Entire body bare. Epistoome defined anteriorly by a very stout spine
      1. Merus of chelipeds with a spine at distal end of its posterior margin. Without blood-red spot on carapcae surface
         1. Carapace covered with scattered, coarse granuels, and meshwork patter. Front cut into 4 teeth ..................................................................................................... P. pelagicus
         2. Carapace covered with much smaller granules, without any meshwork pattern. Front cut into 2 teeth ..................................................................................................... P. trituberculatus
      2. No spine on posterior margin of merus of chelipeds. Carapace marked with 3 large blood-red spots ............................................................................................................ P. sanguinolents
   2. Entire body covered with pubercences............................................................. other species

Key to the species of Charybdis:

1. Cardiac region without ridge
   1. First and second antero-lateral teeth more or less truncated, merus of chelipeds with 3 or more than 3 spines, manus of chelipeds with 4 spines and more inflated; carapace with conspicuous cross-like mark ............................................................................................................ C. feriatus
   2. Otherwise ............................................................................................ other species
2. Cardiac region with conspicuous ridge, median and first lateral front teeth not longer than second lateral front teeth .................................................................................................................... C. natator

Key to identification : Shrimps

Key to families of the Penaeoidea:

All members are marine. Chelae present on anterior three periopods; posterior of each abdominal pleuron overlapping anterior of following; reproductive organs developed into large organs (petasma and thelycum); rostrum well-developed; Fourth and fifth pereiopods well-developed.

1. Cervical groove very prominent, reaching dorsal carapace ................................. Solenoceridae
2. Apparent portion of cervical groove far from dorsal carapace .............................. Penaeidae

Key to the genera of the family Solenoceridae:

1. Both upper and lower antennular flagella flattened ............................................ Solenocera
2. Upper antennular flagellum subcylindrical ........................................................ other genera

Key to the genera of the family Penaeidae:

1. 1. Integument smooth; carinae and grooves on carapace apparent ......................... go to 2
   2. Integument thick and rough; carinae and grooves on carapace not apparent ........ go to 3
2. 1. Rostrum with ventral teeth .............................................................................. Penaeus
   2. Rostrum without ventral teeth, telson without fixed lateral spines, rostrum extending far beyond eye & exopod absent on the fifth pereiopod; carapace without longitudinal and vertical sutures ........................ ....................Metapenaeus (Metapenaeus ensis)
3. 1. Pterygostomian or branchiostegal spine present; telson with fixed lateral spines; petasma asymmetrical .................................................................................................................... Metapenaeopsis (Metapenaeopsis barbata)
   2. Otherwise .................................................................................................... other genera

Key to the species of the genus Solenocera:

1. Telson without lateral spines .......................................................................... S. crassicornis
2. Telson with fixed lateral spines ....................................................................... other species

Key to the species of the genus Penaeus:

1. 1. Gastro-frontal carina (groove) present .............................................................. go to 2
   2. Gastro-frontal carina (groove) absent ............................................................... go to 5
2. 1. Telson with movable lateral spines & post-rostral carina without median groove ... P. marginatus
   2. Telson with movable lateral spines & post-rostral carina with median groove ....... go to 3
3. 1. Ischial spine present on first pereiopod ............................................................ other species
      
   2. Ischial spine absent on frist pereiopod ............................................................. go to 4
4. 1. Post-rostral carina wider than adrostral groove; body covered with cross bands; uropods with bright yellow patches .................................................................................................................... P. japonicus
      
   2. Post-rostral carina as broad as adrostral groove; body without cross bands; uropods without bright yellow patches .................................................................................................................... other species
5. 1. Hepatic carina present; body covered with cross bands .....................................go to 6
      
   2. Hepatic carina absent; body without cross bands ..............................................go to 7
6. 1. Exopod present on the fifth pereiopod; adrostral groove extending posteriorly behind first post-rostral tooth; hepatic carina situated at 30° with dorsal carapace......................................................................... .......other species
      
   2. Exopod absent on the fifth pereiopod; adrostral groove ending before reaching base of first post-rostral tooth; hepatic carina parlleled to dorsal carapace ............................................................................................P. monodon
7. 1. The third pereiopod overreaching tip of scaphocerite .........................................P. penicillatus
      
   2. The third pereiopod not reaching tip of scaphocerite ..........................................other species

Key to identification : Mantis Shrimps

Key to the families:

1. 1. The inner spines of the cheliped not more than three ........................................ other families
   2. The inner spines of the cheliped more than three .............................................. go to 2
2. 1. The length and width of carapace are nearly equal ............................................ other families
   2. The length and width of carapce are not equal ................................................. Squillida

Key to the genera of the family Squillidae:

1. Carapace and abdominal surface with rough net-like appearance ....................... Dictyosquilla (Dictyosquilla foveolata)
   
2. Carapace and abdominal surface without net-like appearance ............................ Oratosquilla

Key to the species of the genera Oratosquilla:

1. Body surface with black spots ........................................................................ O. kempi
   
2. Body surface without black spots ................................................................... O. oratoria

Key to identification : Lobsters

Key to the families:

1. Body as half cylindrical shape, without eye orbital; the second antenna with long antennule ............................................................................................................................ Palinuridae
   
2. Body flattened, with eye orbital; the second antenna without long antennule ........................................................................................................................... other families

Key to the genera of the family Palinuridae:

1. Carapace longitudinal in shape, rostrum linked; the first antennule rather short and its part covered by the lower part of second antenna ........................................................................................................................... other genera
   
2. Carapace cylindrical in shape, rostrum separated; the first antennule long, and its part not covered by the lower part of the second antenna ............................................................................................................................ Panulirus

Key to the species of the genera of Panulirus:

1. Abdominal segments with two narrow deep black bands separated by intense white band ..................................................................................................................... P. versicolor
   
2. Otherwise...................................................................................................... go to 2
2. 1. Lateral sides of abdominal segments with hairy depressions.............................. P. stimpsoni
   2. Lateral sides of abdominal segments smooth, without depression....................... P. ornatus

Key to identification : Gastropods

Key to the families:

1. 1. Shell extremely compressed spiral with very wide aperture; with row of perforations .................................................................................................................... Haliotidae (Haliotidae diversicolor)
      
   2. Shell not compressed and without row of perforations ....................................... go to 2
2. 1. Thick outer lip with small aperture .................................................................. Strombidae (Strombidae luhuanus)
      
   2. Thin outer lip and large aperture ..................................................................... go to 3
3. 1. Apex often terminated in large embryonic whorl; with folded columella ............... Volutidae (Melo melo)
      
   2. Apex not terminated in large embryonic whorl and without folded columella ........ go to 4
4. 1. With conspicuous true or false umbilicus; short siphonal canal ......................... Buccinidae
      
   2. Without conspicuous umbilicus; long siphonal canal ........................................ Melongenidae

Key to the species of the family Melongenidae:

1. Spire with angular whorl and small nodules on shoulder; short siphonal canal ............ Hemifusus tuba
   
2. Spire wihout angular whorl and smooth shoulder; long siphonal canal ........................ Hemifusus ternatanus

Key to the species of the family Bcuccinidae:

1. Spiral bands with rectangular brown patches ........................................................... B. areolata
   
2. Surface with irrecgular brown patches ..................................................................... B. lutosa

Key to identification : Bivalves

Key to the families:

1. 1. Equivalve ..................................................................................................... go to 2
      
   2. Inequivalve ................................................................................................... Ostreidae (Crassostrea sp.)
2. 1. Nearly ovate shell ......................................................................................... go to 5
      
   2. Elongate shell .............................................................................................. go to 3
3. 1. Sharp beaks at anterior ................................................................................ go to 4
      
   2. Small bearks near centre .............................................................................. Solecurtidae (Sinonovacula constricta)
4. 1. Hard shell; long hinge line with small teeth ..................................................... Mytilidae (Perna viridis)
      
   2. Brittle shell; toothless hinge .......................................................................... Pinnidae (Pinna pectinata)
      
5. 1. Shell with strong radial ribs ............................................................................ go to 7
      
   2. Shell without strong radial ribs ....................................................................... go to 6
6. 1. Shell surface with a great variety of concentric or radial sculpture ...................... Veneridae
      
   2. Shell surface without sculpture, only with concentric ridges .............................. other families
7. 1. Shell with ears .............................................................................................. Pectinidae
      
   2. Shell without ears ......................................................................................... Arcidea (Scapharca subcrenata)

Key to the genus of the family Pectinidae:

1. Right valve often different in color from left valve, without radial ribs; small ears ............................................................................................................................ Amusium (Amusium pleuronectes)
   
2. Two valves often equal in color; strong radial ribs; large ears ..................................... Chalamys (Chalamys nobilus)

Key to the genus of the family Veneridae:

1. Moderately compressed, rhomboidal shells with umbones well towards anterior end .... Tapes
   
2. Inflated ovate shells with umbones near the centre ................................................... Meretrix (Meretrix lusoria)

Key to the species of the genus Tapes:

1. Shell surface with zig-zag lines and irregular blotches .............................................. T. literatus
   
2. Shell surface without zig-zag lines and irregular blotches, but radial markings ............ T. philippinarum

Key to identification : Cephalopods

Key to the order of the class Cephalopods:

1. 1. Body with fins ............................................................................................... go to 2
      
   2. Body without fins .......................................................................................... Octopoda
2. 1. With supplementary eye-lid ............................................................................ Sepioidea
      
   2. Without supplementary eye-lid ........................................................................ Teuthoidea

Key to the family of the order Octopoda:

1. Mainly benthic octopods without an external shell and without dorsal and ventral water pores on the head ............................................................................................................................ Octopodidae
   
2. Pelagic octopods either with a coiled external shell or dorsal and ventral water pores on the head ............................................................................................................................ other families

Key to the genera of the family Octopodidae:

1. Typical octopods with two rows of suckers, the third right arm usually strongly hectocotylized in the males, and without pouches and pores between the arm bases ........................................................................................ Octopus (Octopus membranaceus)
   
2. Octopods with two rows of suckers, the third right arm only slightly lmodified in the males, and with a pouch or pocket and pore between the base of the arms on the oral surface ...................................................................... other genera

Key to the family of the order Sepioidea:

1. Shell is a thick, layered chalky or calcium carbonate structure; fins marginal bordering nearly the entire side of the mantle ............................................................................................................................ Sepiidae
   
2. Shell vestigial and chitinous or absent. Fins separate, paddle-shaped or crescentric ... other families

Key to the genera of the family Sepiidae:

1. No pore present ................................................................................................... Sepia (Sepia recurvirostra)
   
2. A large pore present posteriorly beneath the juction of the fins ................................. other genera

Key to the suborder of the the Teuthoidea:

1. Neritic squids with the eye covered by the continuous membrane of the head ............. Myopsida (Loliginidae)
   
2. Oceanic squids with the eye open to the water, surrounded by a true continuous eyelid ........................................................................................................................... other suborders

Key to the genera of the family Loliginidae:

1. Fins rhombic, terminal, their length never exceeding 75% of the mantle length; mantle slender to stout, bluntly pointed posteriorly; no median ventral ridge on mantle in males; arms not noticeably short; gladius with curved margins, not thickened ........................................................................................................................... Loligo (Loligo edulis)
2. Otherwise ............................................................................................................ other genera