IDENTIFICATION (with reason) OF Limulus sp. (B.Sc. ZOOLOGY_CCF-CC5_SEM4)

    Identifying features are:

1. Multicellular heterotroph.
2. embryonic development, preceded by heterogametic fertilization.

            Hence, the specimen belongs to the Kingdom Animalia.

1. Segmented body covered by chitinous cuticle.
2. Body segment bear paired externally jointed appendages.
3. Anterior photoreceptors are present.

           Hence, the specimen belongs to the Phylum Arthropoda

1. Body is divisible into cephalothorax or prosoma & opisthosoma.
2. Prosoma bears 6 pairs of appendages.
3. First two pairs of appendages are chelicerae & pedipalpi.
4. Prosoma bears six pairs of appendages.
5. Median Ocelli present.
6. Book gill or book-lung is present.

         Hence, the specimen belongs to the Sub Phylum: Chelicerata

1. Prosoma with chelicerae & 5 pairs of appendages.
2. Opisthosoma is divided into mesosoma & metasoma.
3. Well developed compound eyes.
4. Mesosoma bears 5 or 6 pairs of biramous, lamelliform appendages, except the first one.
5. Telson is present.

          Hence, the specimen belongs to the Class: Merostomata

1.  A hinge divided Prosoma & Opisthosoma.
2. Three segmented Chelicera is present.
3. Presence of six segmented Pedipalpi  with spiny gnathobases.
4. Mouth is elongated & bounded by epistome & chilaria.

            Hence, the specimen belongs to the Sub Class: Xiphosura

1. Prosoma has an unsegmented horse shoe shaped carapace with bent edges to form a doublure.
2. Carapace has one median & two lateral ridges.
3. Opisthosoma has serrated edges. Six pairs of movable spines are present. 
4. Mesosomatic appendages are genital operculum & book gills.
5. Post anal caudal spine hinged and freely movable

           Hence, the specimen seems to be King crab Limulus sp.

Systematic Position (Ruppert & Barnes 1994)

 Kingdom: Animalia

   Phylum: Arthropoda

         Sub Phylum :Chelicerata

                 Class: Merostomata

                    SubClass: Xiphosura

                           Genus: Limulus