Habitat – Wetland – Discover-Nature

Carnivorous Plants

Plants and insects have myriad relationships to one another. Some are mutually beneficial, as when plants offer nectar to feed insects which in turn pollinate the plants. Other relationships only benefit the insects when they feed on leaves, stems, and roots. For carnivorous plants, preying on insects to fulfill their need for nitrogen and other nutrients benefits only the plants.

^{Venus flytrap, Dionaea muscipula by Len Worthington, Aug, 2016}

Pitcher plants are carnivorous, living in bogs and fens found in warm weather areas. In North America, most species are found along the southeastern coastal states from Texas to West Virginia. Bogs are depressions filled with rain or melted snow, while fens are similar but get their water from surface or groundwater. Both types of wetlands are low in oxygen and nitrogen, very acidic, and often quite cold. These characteristics slow down the rate of decay in the vegetation of the wetland, further reducing the availability of nitrogen which is a vital component of chlorophyll, the compound used by plants, along with water, carbon dioxide, and energy, to photosynthesize sugar for food.

^{Tracy’s sundew, Drocera tracyi by Matthew Paulson, May 2022; Venus flytrap, Dionaea muscipula by Judy Gallagher, Jun 2022; White-topped pitcher plant, Sarracenia leucophylla, showing downward hairs by Aaron Carlson, Sep 2013}

Carnivorous plants use several strategies to attract and trap insects. Pitfall traps have slippery faced leaves forming a funnel with a pool of digestive enzymes waiting at the bottom. Downward facing hairs on the leaves make it harder for insects to climb out. Some plants use an opposite strategy and cover their leaf surfaces with a sticky secretion, trapping any insects that land on them. Still others have a leaf-like structure made of two halves that snap together when an insect lands on an inner surface, trapping the insect inside. In both of the last two instances, digestive enzymes are then released to cover, kill, and break down the insect body for absorption by the plant.

^{White-topped pitcher plant, Sarracenia leucophylla, traps separated from flowers by NC Orchid, Apr 2016}

^{Two-spotted bumblebee, Bombus bimaculatus by Judy Gallagher, Jun 2022}

Carnivorous plants are insect pollinated and must be able to attract pollinators without trapping them. All of the plant species go through a dormant period as seasonal temperatures get cooler. Traps die back and are regrown when warmer weather returns. In several species, flowers bloom and attract pollinators with nectar, completing fertilization before traps develop. Other plants separate the flowers and traps by a physical distance. Traps usually lie close to ground level to attract crawling insects, and flowers are grown on top of tall stalks to attract flying insects. A third method is to make the flowers less attractive to potential prey, and make the traps less attractive to potential pollinators. This is achieved by using different colors, patterns, and scents on flowers and traps.

^{Metallic green sweat bee, Agapostemon sericeus by Dann Thombs, Aug 2008}

^{Cobra lily, Darlingtonia californica by Charles Peterson, Mar 2018}

Whether you are growing these unique plants at home or viewing them in a botanical garden or out in the wild, some of the plants and their pollinators to watch for include the white-topped pitcher plant, Sarracenia leucophylla and the two-spotted bumblebee, Bombus bimaculatus; the cobra lily, Darlingtonia californica and the mining bee, Andrena nigrihirta, Tracy’s sundew, Drosera tracyi and the metallic green sweat bee, Agapostemon sericeus, and the Venus flytrap, Dionaea muscipula and any of the hoverfly species, Toxomerus sp.

^{Bog landscape by Chris Moody, Jun 2009}

Aquatic Insects

Rivers and streams meander, fall, swirl, pool and flow through landscapes based on how their channel has been shaped and filled. Moving water, referred to as a current, goes in different directions and speeds as it flows. Currents are slower on the water’s surface, sides, and bottom due to friction with air, soil and rock. The fastest current is just below the surface where nothing impedes its progress, and the slowest is where the water pushes in all directions due to obstacles in its path.

^{Woodland stream by John Holmes, Getty Images}

Aquatic insects living in these turbulent waters employ a variety of methods to anchor themselves in place to breathe and eat. Most aquatic insect species are in their larval stage and will leave their aquatic environment when they become adults. Some are benthic species living attached to the bottom; some are swimmers commonly found in slower moving water; some live in the swift-moving current.

^{Water Penny by Cliff White; Stonefly larva by Jim Rathert, Riffle beetle by Cliff White, all images courtesy of Missouri Department of Conservation}

Most insects must be able to securely anchor themselves to breathe and eat. The water penny, a flow-adapted insect, uses its whole body, a flattened oval disc, to adhere itself to a rock using suction. With its smooth back and with no protrusions, water easily flows over and around this species. Where the current flows around rocks on the bottom, an area of quiet water forms just behind each rock. The caddisfly builds a case around itself from rocks, sticks, and mud and remains in this quieter area. Stoneflies and riffle beetles use sharp hooks at the ends of their legs to hang onto the bottom substrate even while walking about in the flowing water. Where water pools and currents slow after a sandbar, mayflies, crane flies, and midges live in burrows in the silty bottom.

^{Pseudiron mayfly by Dave Ostendorf, courtesy Missouri Department of Conservation}

Mosquito larva courtesy Missouri Department of Conservation

^{Damselfly nymph by Cliff White, courtesy Missouri Department of Conservation}

For animals with lungs, muscles expand the lungs pulling in air where oxygen can be absorbed into the blood stream and transported to cells in the body. Insects do not have lungs but use air tubes attached to spiracles, openings on the outside of their bodies that can be opened or closed. A fine network of air tubes allow oxygen to be absorbed directly by each cell. Damselfly, mayfly, and stonefly use gills to extract oxygen from flowing water and pump it into their air tubes. Mosquitos and water scorpions use snorkeling, where a breathing tube connected to a spiracle breaks the water’s surface. Water beetle adults trap a bubble of air under their wing covers when they dive. It is held in place by hairs on their bodies and covers the spiracles located along the sides of the abdomen.

^{Caddisfly larva with pebble case by Jim Rathert, courtesy Missouri Department of Conservation}

^{Caddisfly larva with plant fiber case by Jim Rathert, courtesy Missouri Department of Conservation}

In addition to oxygen, water currents bring a steady supply of food downriver and carry away waste. In forested streams, vegetation and decaying animals falling into the water provide a variety of food. Midges are able to collect tiny particles of plants and animals found in slow-moving water. Some species of stonefly and caddisfly are shredders, feeding on vegetation moving past them by chewing it into small bits. Filter feeders, including black fly and riffle beetles, use nets and fans to trap particles from faster-moving currents.

^{Midge fly larva by Cliff White, courtesy Missouri Department of Conservation}

^{Crane fly larva by Jim Rathert, courtesy Missouri Department of Conservation}

In areas exposed to lots of sunlight, algae and aquatic insects are the main food sources. Mayfly, caddisfly, and water pennys scrape algae from rocky surfaces. Other species of stonefly and riffle beetles are predators and use their hooked feet to position themselves in steady currents where they are able to snag other species being swept along. Another predator, the alderfly, burrows its bottom into the streambed to catch prey swimming nearby. Damselfly larva may anchor themselves to the bottom or fill a bladder at their rear end with water and expel it with enough force to propel themselves through the current to snag prey.

^{Alderfly larva courtesy Missouri Department of Conservation}

Whether the current is fast or slow, flowing through clear areas or obstacles, streams provide insects with numerous places to live. On you next walk along a waterway, consider all that is happening just below the surface.

Duck Potato Salad

Walking around a freshwater marsh, we can observe dozens of plants and animals. Daily sunlight provides hours of energy, but it is only usable by the plants, which create their own food in a process called photosynthesis. Plants may be fully submerged, floating, or living above the water’s surface, but all are vital components of the food supply.

^{Marsh panorama by Beyond_Invisible, Getty Images}

Just as animals breathe, plants also need to exchange gases, taking in carbon dioxide and releasing oxygen. Plants living in a marsh, where they are fully or partially saturated with water, have developed several strategies for the gas exchange process. Spongy tissue is a universal adaptation of marsh plants. Both stems and leaves contain large airspaces surrounding food producing cells which are well distributed throughout the plant. Airspaces also keep the plants lightweight and enable stems, leaves and flowers to float on or reach above the water’s surface.

Floating wisps of green algae are primitive plants that have been on earth for over two billion years and are the basic food source for all life in the marsh. Millions of microscopic animals, crustaceans, insects, and small fish depend directly on green algae for their food. Green algae lack stems, leaves and flowers, but grow as long chains of nearly identical cells. Some algae are microscopic, some can be easily observed as green strands on or below the water’s surface and some grow to several hundred feet in length.

^{Duckweed forest pond by Sunsju, Aug 2019}

Duckweeds refer to a group of tiny, flowering plants that float on the surface of wetland areas. They reproduce by dividing their cells. This is a rapid process taking from 16 to 48 hours. In optimal growing conditions, with plenty of sunlight and nutrients available, the surface area of a pond can be covered in a very short period of time. Several species of pond plants grow long, narrow leaves with soft, nourishing cells providing a easy-to-eat and tasty treat for marsh dwellers. With large airspaces, these plants are able to stay afloat no matter how long they grow.

^{Spatterdock by Kirill Ignatyev, Jul 2011}

Plants with floating leaves, such as spatterdock, must have a method for preventing excess water from entering leaves and stems when they exchange gases. Plants have stomata, openings in the leaf where gases are exchanged. In terrestrial plants, stomata are located on the undersides of leaves to prevent rain from entering the opening. Floating leaves have stomata on the upper side of the leaf, providing far less exposure to water.

^{Water marigold by Gennady Alexandrov, May 2014}

Water marigold has two types of leaves, one that grows on the stem above the water’s surface and another that grows on the submerged stems. Leaves growing in air take in carbon dioxide and release oxygen through their stomata. Submerged leaves have very thin cell walls and exchange the same gases directly with the water surrounding them.

^{Arrowhead with bulb, -duck potato’, lower right, by Andriy Nekrasov, Getty Images}

Arrowhead is firmly anchored in the bottom of ponds, and has stems, leaves, and flowers growing above the surface. It reproduces by both seeds grown from pollinated flowers and bulbs grown on submerged stems. Bulbs remain submerged, attached to the stem and grow until they are mature enough to anchor themselves in the bottom silt and start another plant. While growing, the bulbs are very tasty and are a favorite food of many duck species, earning the nickname duck potatoes.

^{Wild celery, Vallisneria americana, by Schizoform, Jun 2022}

Wild celery produces both male and female flowers. Female flowers are attached to long stems that float on the water’s surface. Male flowers break off underwater and float to the surface unattached, where they are blown around until they meet a female flower, transferring pollen by contact. The pollinated flower coils downward back under the surface where the seeds develop and are released into the water to start a new plant wherever they land on the silt bottom.

Marsh plants come in many forms and each is well adapted to the unique conditions of the habitat in which they live.

Lakes & Ponds

Pond & lake observations on the trail

Walking trails in northern Illinois are found among many lakes and ponds. Over time, these bodies of water have formed and disappeared at varying rates, providing habitats for wildlife and vegetation.

Quiet mornings at the dock, Maple Hill, KS by RisingThermals, Aug 2021

Several types of water features were formed by the action of the last glaciers that left this area about 13,000 years ago. Kettle lakes were created when large blocks of ice, buried in the rocky edges of retreating glaciers, finally melted, leaving a hole filled with water. Surface lakes also resulted from glacial debris blocking off rivers and streams.

The Oxbow at The Wild Center, NY, Jun 2017

During heavy rainfall, some rivers collect enough water to force a new flow straight through the landscape leaving an older channel cut off into an oxbow lake. As rivers slow and shrink, beavers move in to dam them and create new ponds. Limestone lies under much of Illinois topsoil, dissolving slowly in running water, opening up sink holes that quickly fill to form new lakes.

Ponds and lakes constantly gain and lose water. Water comes in from rainfall, rivers and streams, groundwater, and springs. Water is lost through rivers and streams, groundwater aquifers, and evaporation. Incoming water often carries mineral and organic sediments, slowly filling in the basin. In areas where shorelines are not exposed to wind and wave action, seeds floating on wind and water will begin to take root.

Emergent wetland at Eugene Field by US Army Corp of Engineers, Jun 2014

Ponds and lakes come in many sizes, with shorelines that gradually recede to deeper water or fall off quickly. On the surface, water molecules are attracted to each other to form a firm layer between the water below and the air above. Some organisms use the top side of the surface layer to land on, float on, or run across. Insects, snails, and microorganisms hang off the underside of the surface layer. Where sunlight penetrates, water layers are teeming with single-celled green organisms providing an abundant food source for aquatic wildlife. Shallow lake bottoms support emergent plants, rooted in bottom soil and sending shoots above the surface for air and sunlight.

Cattails around the pond by Jemma Marycz, Jun 2016

Reeds at Keighley Tarn, by Tim Green, Oct 2009

Reeds, grasses, and other marsh vegetation colonize shorelines and shallow areas. Tall vegetation catches and traps wind-blown particles. Sediment comes in from streams and rivers running through the vegetation, gets filtered out and added to the soil layers. As more plants grow on the edges, and soil deposits become denser, woody shrubbery start to move in. Given time, in a natural process, existing lakes and ponds will become ever smaller.

Many lakes and ponds are affected by human activities, slowing down the natural cycle. Dredging and removal of edge vegetation reduces the amount of accumulated sediment. In urban areas, open ground that used to catch rainwater and allow it to slowly filter into wetlands is being covered with impermeable surfaces including roads, buildings, and parking lots. Increased runoff from these surfaces flows quickly into existing lakes and out again just as fast, keeping vegetation from getting an anchor.

Anderson Japanese Gardens, Rockford, IL by Jpellgen, May 2018

As you wander the trails, be sure to observe the differences in lakes and ponds of all varieties, and the many plant and animal species supported by each.

Spring Wetland Vegetation

Early spring vegetation provides egg laying opportunities & protection

In early spring, when temperatures are still cool at night and daylight hours are just starting to lengthen, most plants are just starting to become active. Many amphibian and bird species also start their breeding activities at this time of year, and some of those depend on wetlands for egg laying sites, nesting material, food, and protection. Wetland vegetation creates important habitat for these species.

Emergent wetland at Kino Environmental Restoration project by Desert LCC, Aug 2018

Emergent plants are non-woody species that are rooted in wetland bottoms, but grow tall and emerge above the surface of the water. There are three categories of emergent plants that are important to pond life, including narrow-leaved emergents, broad-leaved emergents, and tall-robust emergents. Additional plants that affect wildlife populations in wetlands include floating plants, shrubs and trees.

Common bur reed, Sparganium eurycarpum, by USFWS Mountain-Prairie, Jul 2008

Common beggar’s ticks, Bidens frondosa, by Gertjan van Noord, Jul 2020

Marsh smartweed, Persicaria amphibia stipulacea, by Tom Wilberding, Aug 2020

Blue-joint grass, Calamagrostis canadensis, at Silver Lake, Utah, by Andrey Zharkikh, Aug 2014

Water willow, Justicia americana, by peganum, Jul 2017

Horsetail, Equisetum arvense, by delirium florens, May 2020

Narrow-leaved emergent plants are grasslike, with narrow stems and leaves, and grow to less than six feet in height. They come from the plant families that include sedges, Carex; rushes, Juncus; and bulrushes, Scripus. Some common narrow-leaved emergents of northern Illinois are common bur reed, Sparganium eurycarpum; horsetail, Equisetum arvense; reed canary grass, Phalaris arundinacea; and blue-joint grass, Calamagrostis canadensis. They provide cover for tadpoles and stems for perching birds to call from. Underwater stems are used to anchor frog egg sacs, and above surface leaves are used for egg laying by several species of dragonflies and damselflies.

Spot-tailed dasher, Micrathyria aequalis, on emergent vegetation by Allan Hopkins, Dec 2012

Eggs sacs anchored on emergent vegetation by JW112211, Apr 2006

Broad-leaved emergent plants are characterized by leaves almost as wide as they are long, and they grow to under three feet in height. Common species in northern Illinois include marsh smartweed, Persicaria amphibia stipulacea; common beggar’s ticks, Bidens frondosa; and water willow, Justicia americana. With broader leaves, these species provide excellent protection for adult and juvenile amphibians.

Cattail marsh at Jay Meiner Wetlands by Justin Meissen, Aug 2006

Tall-robust emergent plants are 5′ to 9′ tall when mature. Leaf and stem sizes vary greatly. In winter, some of the plants may die back or collapse, but many species grow in tightly packed stands where portions of the plant group will survive the entire winter. Examples in northern Illinois include narrow-leaved cattail, Typha angustifolia and broad-leaved cattail, Typha latifolia. In addition, common reed, Phragmites australis, is a highly invasive species found throughout our area.

Tadpole under duckweed by Helena, Jun 2007

Two other groups of plants are important to early spring wildlife. Shrubs, woody plants from 3′ to 9′ tall, and trees, woody plants over 9′ tall. Growing on wetland banks or in shallow water, trees and shrubs have branches and leaves that may be submerged or growing just above the surface. These provide perches for calling species, and some may be used for egg-laying sites. Common species in our area include blue-fruited dogwood, Cornus obliqua; silver maple, Acer saccharinum; and buttonbush, Cephelanthus occidentalis. Floating plants only grow on the surface where there is several inches of water. They are good indicators of water depth and the extent of open water in wetlands. They provide cover for many underwater eggs and juveniles. Duckweeds of the Lemna family and pond lilies in the Nuphar and Nymphaea families are common floating plants in this area.

Buttonbush, Cephelanthus occidentalis, by Jenny Evans, May 2008

Wetlands with emergent vegetation and stable water levels provide healthy habitat for bird, insect, and amphibian breeding populations. As you are out walking this spring, be sure to look at wetland vegetation and how it is used by the wildlife populations living there.

Turnover

Area ponds have been frozen for the last several weeks due to the extremely cold temperatures we have experienced. But, thawing started last weekend which initiates turnover, the mixing of pond water as surface temperatures change with the progression of the seasons. This process happens several times each year, and has profound effects on the insects, amphibians, fish and other wildlife that live in these waters year-round.

Water can exist as a gas, a liquid, or a solid depending on its temperature. Water density and its capacity for carrying oxygen also changes with temperature. Like most other liquids and gases, cold water is heavier, denser and can hold more oxygen than warm water. However, water has a unique property in that it reaches maximum density at 39˚F (4˚C). As water gets colder, it expands, becoming lighter weight and less dense. At 32˚F (0˚C), water freezes into a solid, crystalline structure called ice, which floats on top of the denser water below. This property makes it possible for wildlife to survive below the ice.

During summer, deeper bodies of water will have layers differentiated by temperature. The top layer is warmed by the sun and atmosphere and is the warmest, with layers getting progressively cooler as the pond gets deeper. Plant matter that falls in the pond will start the process of decomposition, using light and oxygen. As decomposing material sinks to the bottom where there is less light, this process can rapidly use all of the oxygen in the lower layers. Most animal life is found in the upper layers at this time of year.

Painted Turtle, *Chrysemys picta* by Steve Hinshaw

The top layer of water is constantly picking up oxygen from wind and wave action. As atmospheric temperatures start to drop in autumn, the top layer becomes colder, denser and able to carry more oxygen. As winter progresses and temperatures continue to drop, the denser, heavier water accumulates on the bottom of the pond. Aquatic species will move to this highly-oxygenated layer to spend the winter. In spring, as ice melts, the top layers of the pond pick up more oxygen from wind and wave action. As water temperatures at the surface start to climb, approaching 39˚F (4˚C), the layering effect may disappear for a short period as the entire pond mixes to a uniform temperature and density. Wildlife will start to move toward surface areas, finding well-oxygenated water everywhere in the pond. Layering will return as top layers warm more rapidly than underlying water.

American Bullfrog, *Lithobates catesbeianus* by James Harding

Northern Leopard Frog, *Lithobates pipiens* by James Harding

In Dupage County, Northern Leopard Frogs, Lithobates pipiens, American Bullfrogs, Lithobates catesbeianus, and adult Painted Turtles, Chrysemys picta, all spend the winter underwater. Painted Turtles burrow into the mud at the bottom. They slow their metabolism down to where they only need a small amount of oxygen each day. The blood vessels in their butts are very close to the skin, and they are able to absorb oxygen from the water directly into their bloodstream. They can remain in this state for 3-4 months. Northern Leopard Frogs and American Bullfrogs also slow down their metabolisms and have a similar ability to absorb oxygen through the skin into the bloodstream. They rest on the bottom, not immersing themselves in the mud because this would prevent the oxygen rich water from being in contact with their skin.

There are many factors that affect turnover and the availability of oxygen-rich water for the animals that overwinter under the ice. A mild winter may not freeze over the ponds, leaving the water well mixed and oxygenated throughout the season. Topography of the land surrounding a pond is very important. Open ponds that receive a lot of sunlight tend to turn over rapidly and often, and will have a shorter period under ice with lots of oxygen-rich water available. Ponds closed in by land or forest canopy will experience much less wind and wave action resulting in little turnover and smaller amounts of oxygen in the water. As spring starts to arrive, be on the lookout for changing conditions as wildlife starts to emerge.