Zooplankton Dichotomous Key




Yüklə 87.39 Kb.
tarix30.04.2016
ölçüsü87.39 Kb.
Zooplankton Dichotomous Key

START HERE with question #1…

1a. Small, simple structure, usually single-celled; or as solitary, circular eggs, or shells, usually < 0.3mm

If yes go to #2

Forams, Acantharians/Radiolarians, Ciliophorans, Tintinnids, Fish eggs, Other eggs, Crustacean nauplii/cyprids



1b. Not Small, instead multi-celled, complex body plan, usually > 0.3mm

If yes go to # 5


ETC.







2a. Small, single-celled, solitary, may have rigid, intricate shells

If yes go to # 3

Forams, Acantharians/Radiolarians, Ciliophorans, Tintinnids



2b. Small to large, spherical, gelatinous, transparent, with some internal structure apparent as yolk or embryo. May be up to 3 mm in size

If yes you’re done!


Fish eggs, Other eggs



2c. More than single-celled, simple body plan; close inspection reveals appendages with setae and segmentation, not spines

If yes you’re done!


Crustacean nauplii/cyprids



3a. Rigid, intricate shells, close inspection reveals perforations in shell, may have spines on shell

If yes go to # 4


Forams, Acantharians/Radiolarians



3b. Small, single-celled lined with cilia

If yes you’re done!

Ciliophorans, Tintinnids








4a. Single, angular or triangulate, shell, with spines OR spines radiating from a circular shell. Having Actinopoda – stiffened pseudopodia that extend radially

If yes you’re done!



Acantharians/Radiolarians




4b. Circular, often multi-chambered shells, having gran-reticulose pseudopodia – that branch and fuse forming a net

If yes you’re done!


Forams







5a. Nudibranch or sea slug like
If yes you’re done!


Nudibranchs

5b. Fish like
If yes go to # 19

Fish larvae, Appendicularia



5c. Squid like
If yes you’re done!


Cephalopods



5d. Crustacean like, segmented body, jointed appendages
If yes go to # 13

Ostracods, Copepods, Isopods, Cladocerans, Amphipods (gammarid), Amphipods (hyperiid), Mysids, Euphausids, adult Decapods (shrimp), larval Decapods (shrimp), larval Decapods (crabs), larval Decapods (lobster/hermits), larval Stomatopods



5e. Shelled: snail or clam like
If yes go to # 6

Ostracods*, Pteropods, Pelagic snails*, Heteropods*

Ostracod picture,




5f. Worm-like, slender body, may be segmented or not
If yes go to # 8

Chaetognaths*, Nemetods, Polychaetes, Appendicularia



5g. Gelatinous or transparent
If yes go to # 9

Pelagic snails*, Chaetognaths*, Salps/Doliolids, Cnidarian medusa, Siphonophores, Ctenophores








6a. Shell hard, brittle, close inspection confirms non-segmented body

If yes go to # 7

Pteropods, or Other Snails



6b. Shell soft, actually carapace covering segmented body of crustacean

If yes you’re done!


Ostracods










7a. Shell whorled or snail-like (dextral coiling)…or compressed or flattened shell, with noticeable keel

If yes you’re done!


Other snails



7b. Shell whorled or snail-like and rounded (sinistral coiling), OR shell bi-laterally symmetrical, many possible shapes

If yes you’re done!


Pteropods







8a. Non-segmented slender body, transparent
If yes go to # 20


Chaetognaths*, Appendicularia






8b. Non-segmented slender body, no recognizable head
If yes you’re done!


Nemetods



8c. Segmented body, paired bristles or setae on each segment, head segment recognizably different from end segment.
If yes you’re done!


Polychaetes








9a. Close inspection reveals radial symmetry, 8 rows of cilia or ctenes
If yes you’re done!


Ctenophores



9b. True jelly with radial symmetric swimming bell, or swimming bell more cone shaped and rigid
If yes go to # 10

Cnidarian medusa, Siphonophores



9c. Close inspection reveals complex, internal structure, namely notochord, muscle bands and gill bar. Tube or barrel shaped
If yes you’re done!


Salps/Doliolids



9d. Long, slender, transparent body showing little internal features
If yes go to # 12


Pelagic snails, Chaetognaths






10a. Swimming bell cone shaped and rigid (bract or nectophore) with no visible stinging tentacles OR, colonial hydrozoan, with visible stinging tentacles such as:

Porpita, Physalia, Vellela
If yes you’re done!


Siphonophores




10b. True jelly with radial symmetric swimming bell and visible tentacles
If yes you’re done!


Cnidarian medusa
















12a. Gelatinous body, close inspection reveals ‘fin’, small snail shell and head
If yes you’re done!


Pelagic snails (Heteropod)


12b. Non-segmented slender body, transparent, close inspection reveals bristles along rounded head
If yes you’re done!


Chaetognaths









13a. Segmented body and appendages may be tucked inside shell-like carapace, eyes may or may not be readily apparent
If yes go to # 14

Ostracods, or Cladocerans





13b. Segmentation may be apparent. Elongate body with separate sections: head segment oval with antennae, appendages and eye-spot often visible, tail segment narrow, no appendages, often forked

If yes you’re done!


Copepods



13c. Segmentation apparent but no separate body sections, each segment with appendages from head to tail section, paired eyes often visible and generally black
If yes go to # 15

Isopods, Amphipods (gammarid), Amphipods (hyperiid)





13d. Segmentation apparent, body segments apparent with appendages, paired eyes easily recognized
If yes go to # 17

Mysids, Euphausids, adult Decapods (shrimp), larval Decapods (shrimp), larval Decapods (crabs), larval Decapods (lobster/hermits), larval Stomatopods











14a. Eye visible and large relative to body size, appendages may by visible outside of carapace
If yes you’re done!


Cladocerans



14b. Eyes not readily visible
If yes you’re done!

Ostracods










15a. Segmented body, laterally compressed, crescent shaped

If yes go to # 16

Amphipods




15b. Segmented body dorso-ventrally compressed, not crescent shaped, eyes as paired, black spots
If yes you’re done!

Isopods







16a. Eyes simple black spots
If yes you’re done!

Amphipods (gammarid, caprellid)




16b. Eyes large, complex, may not be black

Amphipods (hyperiid)







17a. Elongate barrel body, segmented with appendages, posterior end of carapace not firmly attached (shield like), narrow abdominal segments with small appendages, tail segment has rounded organ, called a statocyst. (Adult)

If yes you’re done!

Mysids


17b. Elongate barrel body segment with appendages, carapace firmly attached, abdominal segments with more prominent appendages. Gills visible beneath carapace. (Adult)
If yes you’re done!


Euphausids



17c. Carapace, flat and broad with prominent spines, large claws
If yes you’re done!

larval Stomatopods





17d. Main body firm, box-like or domed and often with spines, paired eyes readily visible. Abdominal section narrow and often curved under main body

If yes you’re done!

True Crabs (brachyuran larvae)


17e. Shrimp like
If yes go to # 18

adult Decapods (shrimp), larval Decapods (shrimp), larval Decapods (lobster/hermits)









18a. Carapace elongated, barrel shaped, firmly attached to all segments, no gills visible, large appendages on abdomen, close inspection reveals some spines, or teeth on carapace. (Adult)
If yes you’re done!


Shrimp (adult)



18b. Carapace LESS elongated and barrel shaped, but still firmly attached to all segments, no gills visible, NO appendages on abdomen, close inspection reveals some spines, or teeth on carapace. (Larvae)
If yes you’re done!


Shrimp (larvae)…Be sure to confirm it is not a Euphausid or a Mysid…that distinguishing features for those organisms are not present.



18c. Distinctive carapace OR telson OR spines on abdominal segments
If yes you’re done!


Other Crabs (anomuran larvae)



18d. Distinctive carapace OR telson OR spines on abdominal segments
If yes you’re done!


Lobster (larvae)


19a. Body an amorphous gelatinous ‘house’ and no eye visible. Tail distinctly narrower than body
If yes you’re done!


Appendicularia




19b. Body and tail continuous, eyes apparent
If yes you’re done!


Fish larvae











20a. Close inspection reveals bristles around head
If yes you’re done!


Chaetognatha



20b. NO bristles around head

Appendicularia






Verilənlər bazası müəlliflik hüququ ilə müdafiə olunur ©azrefs.org 2016
rəhbərliyinə müraciət

    Ana səhifə