Aquatic Macroinvertebrates

What are Aquatic Macroinvertebrates?

Macroinvertebrates are small organisms that do not have a backbone.

A great diversity of types. Insects Spiders Leeches Snails and clams Worms

What are Aquatic Macroinvertebrates?

Aquatic macroinvertebrates are those that live in water.

The majority of aquatic macroinvertebrates are insects Insects can have three different life

stages: larvae, pupae, and adult Which stage is aquatic depends on the

type of insect

Insect Lifecycles - Incomplete Metamorphosis

Some insects do not have a pupae

They molt from a larval form to the adult

Insect Lifecycles - Complete Metamorphosis

What are Aquatic Macroinvertebrates?

For most insects it is the larval form that is aquatic

Common insect orders that have aquatic larvae but terrestrial adults include Odonata – dragon flies and damselflies Ephemeroptera – Mayflies Plecoptera – Stoneflies Trichoptera – Caddisflies Diptera – Flies and Mosquitos

What are Aquatic Macroinvertebrates?

Beetles, Order Coleoptera, have both aquatic larvae and adults Interestingly, the pupae are often

terrestrial Many of the true bugs, Order Hemiptera,

spend their entire life cycle in the water

What are Aquatic Macroinvertebrates?

While insects are the most common aquatic macroinvertebrates, there is a wide variety of non insect forms Includes members of the Mollusc,

Annelid, and Arthropod Phyla to name a few

Types of Aquatic Macroinvertebrates

I. MOLLUSCS (SNAILS AND CLAMS)

I. Molluscs

A. The Phylum Mollusca is the second largest animal phylum in terms of number of species

While most species are marine (saltwater), two groups are common in North Dakota Clams or mussels (bivalves) – not

usually found in wetlands Snails (gastropods)

I. Molluscs

B. Gastropods – the snails

Several different kinds

Common snails in wetlands include the genus Physa

II. ANNELIDS (WORMS AND LEECHES)

II. Annelida

A. Class Hirudinea – The Leeches Several different types Usually considered indicators of poorer

water quality Probably some exceptions to this

Characterized by suckers on both the anterior and posterior end

Also called blood suckers

II. Annelida

Many are ectoparasites that feed on a blood meal They attach to their host, inject an

anticoagulant and an anesthetic This allows them to feed on a blood

meal usually undetected There are some species that are

vegetarians and some that are scavengers

II. Annelida

B. Class Oligochaeta Aquatic worms - small segmented worms

that live in the bottom sediments of rivers, streams, lakes, and marshes Actually quite a few different kinds Often overlooked because of their small

size Tubifex worms are often used for fish

food

Oligochaetes

III. The Arthropods

Include the insects, crsutaceans, and others

Largest group of aquatic macroinvertebrates

Aquatic Insects

Aquatic insects

There is a great diversity of insect species that are aquatic

Many have an aquatic larval stage, but the adult has wings and lives in the habitat near water

A few groups have an entire life cycle in the water

Aquatic insects

A. Order Ephemeroptera - Mayflies Larvae are aquatic Spend the majority of their life as larvae Adults are short lived – 24 – 48 hours

Where the term Ephemeroptera comes from - ephemeral

Aquatic insects

Many different roles and adaptations Some cling to rocks, others burrow, and

some swim Usually considered indicators of good

water quality

Burrowing mayflies

Hexagenia limbata Usually found in

the bottoms sediments

The small squaregills

Aquatic insects

B. Order Trichoptera - Caddisflies Larval and pupal forms are aquatic Considered to be indicators of good to

moderate water quality In many of the species the larvae form

elaborate cases that they live in

Aquatic insects

Larvae can often be identified by the following features Usually live in a case Have two “legs” on the back of their

abdomenThese have hooks that the animal

uses to anchor itself

Longhorned Case maker-Ceraclea sp.

Northern Case maker larvae with case

Aquatic insects

C. Diptera – Flies and Mosquitoes Larval and pupal stages are aquatic Wide variety – some indicators of good

water quality, others indicate poor water quality

Larvae do not have legs – most are wormlike with very strange features

Crane Fly Larvae

Mosquito – Aedes sp.

Aquatic insects

D. Order Hemiptera – True bugs Spend their entire life cycle in the water –

although many can fly and migrate Mouthparts consist of a tube used for

sucking Many are predators

Mesoveliidae Gerridae Hebridae

Giant water bugs

Water Boatman

Aquatic insects

E. Order Odonata – Dragonflies and Damselflies

Larval forms (called nymphs or naiads) are aquatic

Both larvae and adults are predators

III. Aquatic insects

Both damselfly and dragonfly larvae have a prehensile jaw that they can use to spear prey

Damselfly larvae are usually thinner, have three caudal gills

Dragonfly larvae have a stouter body, caudal appendages are much reduced

Dragonfly Larvae

Jaws of Dragon fly larvae

Odonata Adults

Dragonfly adult Damselfly adult

Aquatic insects

F. Order Coleoptera – Aquatic Beetles Beetles are the most diverse group of

animals on earth Many forms are aquatic

One of the few groups where both larvae and adults are aquatic

While some are considered to have little value in water quality determination, others are useful

Chrysomelidae

Most members of this group are terrestrial

Do not have many obvious adaptations for aquatic life

Found mainly on aquatic vegetation

Haliplidae – Crawling water beetles

Small aquatic beetles

Crawl around on submerged vegetation and debris

Top picture – adult Bottom picture -

larvae

Gyrinidae – Whirlygig beetles

Often found buzzing around on waters surface

Unique in that they have two sets of eyes

Dytiscidae – Predaceous diving beetles

Many different types found in wetlands Both adults and larvae are aquatic Both adults and larvae are predators

Dytiscidae – Predaceous diving beetles – Example adult

Dytiscidae – Predaceous diving beetles – Example larvae

IV. OTHER ARTHROPODS

IV. Other Arthropods

A. Order Amphipoda – Scuds (see picture on previous slide)

Can be very common in some areas One type, the genus Gammarus, is found

primarily in lakes and marshes Larger of the two types found in ND An important forage food for fish in

Devils Lake

IV. Other Arthropods

B. Order Decapoda – the Crayfish Common inhabitants of rivers, streams,

and lakes Only a couple of species in North Dakota Crayfish usually feed at night and are

primarily scavengers Fairly short lived with a life span usually of

2 years or less

Crayfish

IV. Other Arthropods

C. Class Branchiopoda – the water fleas, clam shrimp, fairly shrimp, and others

Water fleas are commonly known as Daphnia

Usually found in lentic waters Their body is covered by a carapace They can be an important part of the food

chain in aquatic ecosystems

Daphnia

Fairy Shrimp

Clam Shrimp