Mission Creek - Holoplankton

MISSION CREEK
MICROORGANISMS
Holoplankton

The water’s of Mission Creek are alive with many different microscopic and macroscopic organisms. This micro world is full of small plants, protozoa, bacteria, and animals. These critters provide the food source for larger organisms. They can also tell us whether the environment is healthy. The microorganims have different roles. Some are authotrophic or can make their own food from the Sun. Some are heterotropic or ingest food including plants and other organisms. Some live their entire live in the water (holoplankton) and others only have their larval stages in the water (meroplankton).

PLANTAE

     Phylum Bacillariophyta
          Class Baccillariophyceae (diatoms)
               Order Pennales
                    Gyrosigma sp.
                    Navicula sp.
                    Surrirella sp.
                    Tabellaria sp.

     Phylum Chlorophyta
          Class Chlorophyceae
               Order Chlorococcales
                    Pediastrum sp.
               Order Zygnemales
                   Closterium sp.
                   Mougeotia sp.

PROTOZOA

     Phylum Ciliophora
          Order Endogenida
              Family Tokophryidae
                    Tokophyra sp.
         Order Gymnostomatida
              Family Colepidae
                    Coleps sp.
         Order Hymenostomatida
               Family Paramedidae
                    Paramecium sp.
                    Urocentrum sp.
          Order Hypotrichida
               Family Euplotidae
                    Euplotes sp.
          Order Peritrichida
              Family Vorticellidae
                    Vorticella sp.

Phylum Actinopoda
Class Heliozoa

Phylum Rhizopoda
Family Amoebidae

ANIMALIA

     Phylum Annelida
          Class Oligochaeta
               Chaetogaster sp.
               Pristina sp.
          Family Tubificidae (aquatic worms)

     Phylum Arthropoda
          Class Crustacea
               Subclass Branchiopoda
                    Cladocera (Water fleas)
                    Macrothrix sp.
               Subclass Copepoda
                    Cyclops sp.
               Subclass Ostrocoda
                    Cypris sp.

Phylum Gastrotricha

Phylum Nematoda

Phylum Platehelminthes
Planaria sp.

     Phylum Rotifer
          Euchlanis sp.
          Philodina sp.
          Squatinella sp.

Holoplankton spend their entire lives as part of the plankton. It includes any organisms whether authotrophic or heterotropic, that is controlled by the water movement in which they reside. However, some components are capable of slight movement.

The authotropic representatives include diatoms and green algae. Heterotropic representatives would include protozoa and small animals like rotifers and gastrotriches. Some arthropods can also live their entire life in the water column including water fleas, ostrocods and copepods. Also Included in this section are organisms that live in the water column as plankton, but can live in the benthic (bottom) environment.

Note: Consult “Quick Identification of Fresh Water Microorganisms” for approximate sizes of organisms shown in this section.”

PLANTAE

Phylum Bacillariophyta (Diatoms)

Unicellular organisms are the primary source of food for zooplankton. Most diatoms are plankton that lack flagella (except the male gametes). Frustules (shells or valves) are overlapping like a “pill” box and are made of opaline silica. They are identified by the frustule by its pores, depressions, striae, costa, raphe, and ornamentations. They possess raphe, which is a slit on the apical valve. Striae are holes (punta/areolae) mainly along the edges. Costae are thickened ribs. They are fresh or marine and contain chlorophyll a and c. They are autotrophic with mainly asexual reproduction. There is over 37,000 species.

Class Bacillariophyceae
Order Pennales
Gyrosigma sp.

The overall shape of the frustule is moderately sigmoid and lanceolate. It gradually tapers to obtusely rounded ends. The axial (top) area and the raphe are sigmoid as well. The proximal ends of the raphe curve in opposite directions and the central area is longitudinally elliptical. The transverse and longitudinal striae are distinct and the transverse striae are slightly radiate. The longitudinal striae curve outward to the sides of the central area

Class Bacillariophyceae
Order Pennales
Navicula sp.

The pennate diatoms exhibit a gliding movement, changing motion without any apparent reason. Striae are perpendicular to the central raphe, which has a characteristic larger area in the center.

Class Bacillariophyceae
Order Pennales
Surirella sp.

Frustules are biraphid and symmetrical to the apical axis. Shape is elliptical to broadly linear in outline. Some species are spirally twisted. The raphe are elevated along the margin of the valves. Striae fine to unresolved.

Class Bacillariophyceae
Order Pennales
Tabellaria sp.

These pennate diatoms usually attach themselved to form large sig-zag chains. They rarely form straight colonies. The ends and central portions of one individual valve are inflated. Striae are fine and costa are absent.

Phylum Chlorophyta (green algae)

The Chlorophyta are very diverse aquatic plants with over 8000 species ranging from fresh to marine conditions. However, about 90% are fresh water. They contain chlorophyll a and b. They store starch as a food reserve inside plastids. The classification is confusing and not agreed upon by researchers. Most green algae have firm cell walls. Some contain flagella while other have calcified shells.

Class Chlorophyceae
Order Chlorococcales
Pediastrum sp.

A colonial algae widely found in freshwater. Multinucleate cells are geometrically arranged in flat, circular plates. Protruding pointed projections can be seen on the surface.

Class Chlorophyceae
Order Zygnematales
Closterium sp.

Pair of cells whose cytoplasm are joined by an isthmus at the location of a single shared nucleus. Pyrenoids run parallel to the cell’s long axis. Lunate or acuate curved.

Class Chlorophyceae
Order Zygnematales
Mougeotia sp.

Mougeotia species are unbranched filamentous green algae. They are cylindrical, with band-, plate- or star-shape chloroplasts. A single chloroplast fills the length of the cell. This chloroplast resembles a twisted ribbon. The chloroplast may be seen lying flat (horizontal) when seen through the microscope. The chloroplast may be twisted and can be seen as a narrow strip up the middle of the cell. Cell walls are parallel. Grows rapidly to produce a type of pond “scum.”

PROTOZOA

Phylum Ciliophora

Ciliates are fresh and marine microbes, covered with cilia. Cilia are short whip-like extensions embedded in the outer cell. Cilia aid in movement during feeding. A variety of organelles plus two kinds of nuclei can be found internally. Ciliophora are heterotrophs feeding on bacteria and other small organic particles. Usually reproduce asexually but also exchange DNA through a process of conjugation.

Phylum Ciliophora
Order Endogenida
Family Tokophryidae
Tokophyra sp.

Protozoa that possesses hollow, sticky tentacles (instead of cilia) to capture prey. Resides on water plants and other organisms.

Phylum Ciliophora
Order Gymnostomatida
Family Colepidae
Coleps sp.

Barrel-shaped body with regularly arranged calcareous plates. Cilia surrounds anterior end with smaller projects near its posterior end. A rapid swimmer and voracious feeder. Eats detritus or dying small organisms.

Phylum Ciliophora
Order Hymenostomatida
Family Parameciidae
Paramecium sp.

Paramecium have a stiff outer covering in a slipper shape. It swims using its short cilia that encapsulated the entire outer surface. It has an external oral grove that leads to a mouth pre. It also has an anal pore. Moves forward in a corkscrew manner, but can reverse directions.

Phylum Ciliophora
Order Hymenostromatida
Family Urocentridae
Urocentrum sp.

Cylindrical, short body with cilia as distinct girdles with a distinct tuft at the rear. An oval shaped Ciliophora with a constriction in the middle. Swims rapidly on its tail in an irregular spiral motion. 50-80 microns.

Phylum Ciliophora
Order Hypotrichida
Family Euplotidae
Euplotes sp.

This cilicate has complex ciliary structures in the cell’s surface. Cell shape is ovoid with tuffs of cilia joined together to act as an organelle.

Phylum Ciliophora
Order Peritrichida
Family Vorticellidae
Vorticella sp.

The genus Vorticella has a bell shaped body with a circle of cilia around the oral opening. A slender, contractile stem helps this group to attach to a substrate (sessile) or to other members of the same species. It forms a colony of many individuals.

Some groups are difficult to speciate so the following descriptions represent larger groups of protozoa

Phylum Actinopoda
Class Heliozoa

Freshwater species with a symmetrical globular form. Possesses radiating axopodia that contains cytoplasm. The axopodia contract bringing bacteria and other nutrients into a food vacuole where it is digested.

Phylum Rhizopoda
Family Amoebidae (naked amoeba)

Amoebas are noted for its slow, free-form motion using pseudopods. The cell wall moves as the cytoplasm shifts within the cell . It captures its food by engulfing its prey with this motion. Specimens found were naked (without a shell) and polypodial (many pseudopods at one time).

ANIMALIA

Phylum Annelida

Annelids have external segments that correspond with repeated digestive and reproductive organs. They live on land, in ocean and fresh water. Fresh water annelids include leeches and bristle worms. Most annelids are predators or scavengers. Swimming annelids actively feed on fish eggs and insect larvae.

Phylum Annelida
Oligochaeta
Chaetogaster sp.

Chaetogaster eats small crustaceans and insect larvae. The prostomium (mouth area) is well developed, pointed in shape with long sensory hairs. The dorsal side does not have setae (hairs), but can be found on the ventral side.

Phylum Annelida
Oligochaeta
Pristina sp.

A segmented worm with characteristic hair setae in bundles along its dorsal side. Prostomum rounded to form proboscis at the anterior end.

Phylum Annelida
Oligochaeta
Family Tubificidae (aquatic worms)

Aquatic worms are close relatives to the earthworm except they are smaller and live in shallow, fresh water. They feed on detritus, bacteria, and algae in the water. They use the same undulating motion that is common movement for earthworms.

Phylum Arthropoda

Arthropods compose the largest group of organisms on Earth. They are characterized by having an external skeleton with jointed limbs. They include both marine and fresh water groups. Some arthropods are total aquatic while others may only live in the water in their larval or nymph stages.

Phylum Arthropoda
Crustacean
Cladocera (water fleas)

Water fleas have large antennae which they use for locomotion. They have large dual compound eyes above the antennae. Five-six feet are used to filter food (small algae) before it goes through its digestive system. You can also observe its very small heart.

Phylum Arthropoda
Crustacean
Copepods

Copepods do not have a shell but are slender and segmented. Cyclops is a common fresh water copepod that has one single eye spot. Females carry two sacs on their tail.

Phylum Arthropoda
Crustacean
Ostracods

Ostracods have characteristic two symmetrical shells that cover its body. The shrimp like critter lives inside. The shell is composed of calcium carbonate.

Phylum Gastrotricha

Gastrotrichs are wormlike animals with lobed heads that are bilaterally symmetrical. The have adhesive tubes mainly near its posterior that help it cling to surfaces. Their bodies are not segmented and are flat. Their head lobe has small bristles on an oral hood.

Phylum Nematoda (roundworms)

Nematodes are cylindrical and slender with rounded ends, which attributes to this group being referred to as roundworms. They lack segmentation and cilia. Nematodes can be found in most habitats including soil, sand, salt flats, ocean, hot springs, and fresh water. There are also parasitic forms.

Phylum Platyhelminthes (flatworms)

These flatworms are ribbon-shaped and are adapted to many habitats including land, marine, and fresh water. They are noted for their extensive regeneration. They are not as complex as the annelids. They have an opening into the gut that acts as food in and waste out portal.

Phylum Platyhelminthes
Planaria

Planaria are easily recognized because their head region has two eyes that appear “cross-eyed.” They are free living and eat decaying meat. They have a simple nervous system. Their excretory system consists of specialized “flame cells,” that remove waste.

Phylum Rotifer

Rotifers are named for the cilia at the crow of their heads. They are bilaterally symmetrical and covered with an external layer of chitin called a lorica. Rotifers lack a circulatory system and respire through the surface of their body. Most are free swimming individuals although some create colonies that can be seen rotating rapidly like a spinning ball. They feed on bacteria, protists, other rotifers and small animals, and suspended organic matter. Rotifers are a major source of food for other animals in freshwater environments.

Phylum Rotifer
Euchlanis sp.

The lorica is transparent and encases most of the rotifer. It feeds on small microorganisms and debris. It uses its 2 rear appendages to move itself around.

Phylum Rotifer
Philodina sp.

A large rotifer that is transparent with easily observed internal organs. Cilia form a rotating wheel organ on the head. The cilia stroke back and forth at very high speed creating a whirlpool that draws food to its mouth. This genera is commonly used in toxicity studies.

Phylum Rotifer
Squatinella sp.

Squatinella has a transparent shield over the head region. Their eyes have lenses. The shield covers the cilia which is on the depressed side and has two pronounced appendages toward posterior end.

PLANTAE Phylum Bacillariophyta Class Baccillariophyceae (diatoms) Order Pennales Gyrosigma sp. Navicula sp. Surrirella sp. Tabellaria sp.

Class Bacillariophyceae Order Pennales Gyrosigma sp.

Class Bacillariophyceae Order Pennales Navicula sp.

Class Bacillariophyceae Order Pennales Surirella sp.

Class Bacillariophyceae Order Pennales Tabellaria sp.

Phylum Ciliophora

Phylum Ciliophora Order Endogenida Family Tokophryidae Tokophyra sp.

Phylum Ciliophora Order Gymnostomatida Family Colepidae Coleps sp.

Phylum Ciliophora Order Hymenostomatida Family Parameciidae Paramecium sp.

Phylum Ciliophora Order Hymenostromatida Family Urocentridae Urocentrum sp.

Phylum Ciliophora Order Hypotrichida Family Euplotidae Euplotes sp.

Phylum Ciliophora Order Peritrichida Family Vorticellidae Vorticella sp.

Phylum Actinopoda Class Heliozoa

Phylum Rhizopoda Family Amoebidae (naked amoeba)