Microorganisms Active day and night

Difflugia acuminata

Cylindrifflugia acuminata

iNaturalist

Meet the microscopic mason of the pond world. Difflugia acuminata builds its own protective armor out of tiny grains of sand, roaming the underwater silt of your backyard pond.

0 Sightings

0 Habitats

Quick Identification

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Size

150-400 micrometers (0.006-0.015 inches) in length

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Colors

Translucent body; shell (test) color depends on gathered materials, ranging from sandy brown to grey or amber

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Key Features

Elongated, vase-shaped shell (test) made of mineral grains
Distinctive pointed 'horn' or spine at the aboral end
Single circular opening for pseudopods
Finger-like, clear lobopodia used for movement

When You’ll See Them

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Activity pattern Active day and night

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Peak hours 24 hours a day

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Season Year-round (most active Spring-Autumn)

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Diet Primarily a consumer of diatoms, green algae, and bacteria scavenged from the sediment.

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Habitat Freshwater environments including the silty bottoms of ponds, lakes, marshes, and peat bogs.

public Geographic range

Where Does the Difflugia acuminata Live?

This species is a cosmopolitan inhabitant of freshwater ecosystems across nearly every continent, with the exception of Antarctica. It is widely distributed throughout North America, Europe, and Asia, thriving in both pristine mountain lakes and nutrient-rich suburban garden ponds. Its ability to form resilient cysts allows it to be dispersed by wind or transported on the damp feathers of migratory water birds, ensuring its presence in almost any permanent body of standing water.

Basemap © OpenStreetMap contributors

8 Countries

150M km² Range

Least Concern Conservation

US United States

16

CA Canada

8

CN China

6

AU Australia

4

BR Brazil

1

eco

iNaturalist / Verified observation data

47 observations

24 research grade

8 countries

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Behavior

Difflugia acuminata is a master architect of the microbial world. Unlike 'naked' amoebae, this species constructs a protective shell called a test by collecting microscopic grains of sand, silt, or the discarded shells of diatoms from its environment. It glues these particles together using a specialized internal cement. This shell provides protection against small predators and environmental shifts, allowing the amoeba to thrive in the complex debris at the bottom of freshwater bodies.

Movement is slow and deliberate. The organism extends finger-like projections called lobopodia through the opening (pseudostome) at the base of its shell. These act as both legs to pull the shell along the substrate and as sensory organs to detect food. While they are solitary hunters, they are often found in high concentrations in areas rich in organic 'marine snow' or biofilm. They do not interact with humans directly, but they are essential players in the microscopic food web, keeping bacterial populations in check.

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Camera Tips

To observe Difflugia acuminata, you will need to move beyond standard trail cameras and utilize a digital microscope camera or a specialized AI-powered 'pond-cam' designed for macro photography. The best place to find them is in the 'benthic' zone—the very bottom of your pond. Use a pipette to collect a small amount of the green or brown 'muck' found on submerged rocks or at the base of aquatic plants like lilies.

For high-quality captures, use a slide with a shallow well to allow the amoeba room to move its shell. Since these organisms are semi-translucent, lighting is your most important setting. Use 'Darkfield' illumination if your camera supports it; this will make the sand grains in the Difflugia's shell sparkle against a dark background, highlighting the architectural detail. If using standard 'Brightfield' light, keep the intensity low to avoid washing out the delicate, clear pseudopods.

Baiting can be done in a petri dish by adding a few drops of a concentrated algae culture or a single grain of crushed fish food. Within a few hours, Difflugia will often crawl toward the food source. Patience is key, as their movement is measured in micrometers per minute. Set your camera to time-lapse mode, capturing one frame every 5–10 seconds, to create a stunning video of this microscopic mason navigating its environment. Ensure the water sample remains cool, as the heat from microscope bulbs can quickly dehydrate or kill the specimen.

Similar Species

Species that look similar or are commonly confused with Difflugia acuminata.

Difflugia oblonga

Lacks the sharp, pointed aboral spine found in D. acuminata, typically having a more rounded base.

Arcella vulgaris

Builds a smooth, circular, chitinous shell that looks like a transparent doughnut rather than a sandy vase.

Centropyxis aculeata

Has a flatter, more pancake-like shell with several spines around the edges rather than one single spine at the top.

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Frequently Asked Questions

Difflugia acuminata are active 24 hours a day. Unlike larger animals, they do not rely on a day-night cycle, though they may move toward or away from light depending on the location of their algal food sources.

The best way to attract them is to maintain a healthy, chemical-free backyard pond with plenty of organic debris and aquatic plants. They love the 'muck' at the bottom of birdbaths and ponds where algae and bacteria naturally grow.

They are omnivorous micro-predators that eat diatoms, various species of green algae, and bacteria. They use their sticky pseudopods to grab food and pull it inside their shell for digestion.

Yes, they are extremely common in suburban garden ponds, drainage ditches, and even damp moss in gutters. If there is permanent freshwater and a source of sand or silt, they are likely present.

Look for the 'test' or shell. While many amoebae are naked blobs, Difflugia acuminata is distinctive for its pear-shaped shell made of visible sand grains and the sharp, pointed 'horn' at the very top (the end opposite the opening).

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