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2 a. Body with radial symmetry: 

COELENTERATA (phylum); 

HYDROZOA (class) 

Craspedacusta, Freshwater medusae
        With small solitary polyps and free-swimming medusae.
        In freshwater. Size 20000 μm (20 mm). 
        Food of polyp and medusae: Asplanchna, copepods.
        Although no recent records are known, it might still 
        be found (Terry L. Peard, Ph.D. personal communication).
        Se lifecycle from (http://www.jellyfish.iup.edu/).

       Craspedacusta sowerbyi, (LANKESTER) 

       (syn. C. sowerbii) 

         [Roxas 1936, in Reisinger, 1972] 

   

2 b. Body with bilateral symmetry.......................................3   

3 a. Small animals with ciliated crown or corona (wheel organ).
        Body without segments. No legs present, 
        with or without tail like foot. Suspension feeding via coronal cilia
        Food: Bacteria, algae, detritus. Planktonic or bentic: 

ROTIFERA, Rotifers or Wheel animacules (phylum)..................7  

  

3 b. Body segmented (with metamery): 

ARTHROPODA, Arthropods (phylum)..................................4

 

4 a. Without jointed legs, (larvae) transparent, except for the black
        air-sacs, of which one pair lies in thorax and one pair lies
        near the end of abdomen. As fig. 4a. 

   (INSECTA, Insects (Class)

            DIPTERA, True flies (order)    

   

     Chaoborus (syn. Corethra), Phantom midge-larvae.
            Third and fourth larval instars planktonic  

            during night, bentic during day. With vertical 
            migration. 
            Food: zooplankton and midge-larvae (Chironomids). 
            In Lake Lanao Chaoborus is responsible for the major
            mortality of its pry (Thermocyclops, Tropodiaptomus, 
            Diaphanosoma, Moina, Bosmina and Keratella). In lakes.
            - Lake Lanao (C.sp = Ekstein 1)
               Chaoborus manilensis, (SHINER)
                  [1969, Lewis 1977, 1979b]    

 

4 b. With legs. 

          CRUSTACEA, Crustaceans (class)................................5   

 

5 a. Without a shell-like covering of the body, with up to five pairs
          of 2-branched swimming legs (might have a 6^th rudimentary 
          pair of leg). Abdomen without appendages. 
          Size 100-2000 μm. Filtratory and/or raptorial.
          Food: Algae, detritus and zooplankton.
          COPEPODA, Copepods (subclass)...............................100 

 

 

5 b. With a shell-like covering, which may or 
          may not entirely cover the body...............................6   

 

6 a. Bivalve shell enclosing the entire body. Body not distinctly
            segmented. Legs not leaf-like. Size 100-1000 μm. Planktonic
            species, omnivorous, feeding on algae and detritus. (Fig. 6a:
            anatomy of ostracod and sample from Laguna de Bay). 
      

OSTRACODA, Mussel shrimps (subclass)
Only few records. Victor (2002) gives a key to 17 genera likely to occur in Western tropical freshwaters.

   Strandesia VAVRA, 1895. (family Cypridacea BAIRD 1845)
   - Lake Lanao, rice fields.
 
   Strandesia wolterecki, TRESSLER 1937.
   (syn. Strandesia chondropherusa Rome, 1965)
   (syn. Strandesia regularis Rome, 1962)
          [1937d, 1981a,b, 2005b(key)]

   Other species of Strandesia found in the Philippines:

   Strandesia. calapanensis Tressler, 1937

   Strandesia. complexa Victor and Fernando, 1982

   Strandesia. sexpunctata Klie, 1932

   Strandesia. purpurascens (Brady, 1886),
    (see 1981a, 2005b(key))

      Endemic species in
      - Laguna de Bay
   Stenocypris derupta VAVRA

   Adapted for benthic life, but frequently appearing in
   plankton collections
      - Mindanao
         [1981a, 2002]
   Cypria (Cypris) spinifera, TRESSLER, 1937

   Planktonic genus.
   Eucypris bayensis, TRESSLER, 1937
          [1941, 1981a,b]

      - Roadside ditch on Camaguin Island, 1932.
   Eucypris orca, TRESSLER, 1937
          [1941, 1981a,b]

   Dominating the invertebrate fauna together with
   Eucyclops serrulatus in
      - Ricefield floodwater, IRRI.
   Heterocypris lozonensis Neale,?. (family Cyprinotinae)   
          [1998b]

Ostracod  from Laguna de Bay

    

6 b. Bivalved shell (Carapace) covers the body but leaves the head free. 
         Legs leaf-like. Size 200-1500 μm. Filtrators, with filter setae
         on the legs. Food: Algae, bacteria and detritus.
          BRANCHIOPODA, Branchiopods (subclass). 
             CLADOCERA, Water fleas (order)
                (Tagalog: Kutung tubig)...............................78

 

 

 

Table: Characteristics of the main groups of freshwater zooplankton. Excerpt after Brandl (2002)
	Rotatoria	Cladocera	Copepoda
Reproduction mode	Parthenogenetic (mostly)	Parthenogenetic  (mostly)	Sexual
Typical adult length μm	200 - 600	200 - 1500	100 - 2000
Food size μm	1 -20	1 - 50	5 - 100
Mode of feeding	Suspension feeding via coronal cilia	Filtratory feeding via thoracic appendages	Filtratory and/or raptorial
Susceptibility to fish predators	Very low	High	Low
Susceptibility to invertebrate predators	Low	Moderate	Moderate to high

 

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