Benthic

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Benthic Macroinvertebrates
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What are Benthic Macroinvertebrates?
Benthic of, relating to, or occurring at the
bottom of a body of water Benthos organisms
that live on or in the bottom of a body of
water Macroinvertebrate spineless animal that
can be retained on a 500 µ (micron) net
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DNR Review Sheet
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Mayflies (Ephemeroptera)

• 3 tails (some have 2)
• Noticeable gills on
• abdomen
• Single claw on each leg
• Wing pads present

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Mayfly gills
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Stoneflies (Plecoptera)

• All stoneflies have two tails
• Gills, if present, are usually found
• on the underside of thorax
• Two claws on each leg
• Antennae are long
• 3 distinct thoracic segments

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2 tails
2 tarsal claws
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Caddisflies (Trichoptera)

• Caddisflies are best known for their nets,
  retreats and portable cases they construct.
• Case made of stone, leaves, or sticks
• Six jointed, hooked legs just behind the head
• No wing pads

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Hydropsychidae common netspinner
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Common netspinner
(Hydropsychidae)
Most Caddisflies
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Common Netspinner
Hydroptilidae (Microcaddisflies)
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Common Netspinner
Hydroptilidae (Microcaddisflies)
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Helicopsychidae
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Dobsonflies, Alderflies, Fishflies (Megaloptera)

• Two Families Sialidae and Corydalidae
• Large jaws
• Pointed feelers along edge of
• abdomen

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Corydalidae
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Sialidae
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True Flies (Diptera)

• Large group and very diverse
• They have recognizable common names
  Mosquito, Black Flies,
  Midges, Crane flies, Horse flies and Deer flies

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True Flies (Diptera)

• Lack jointed thoracic legs
• Most have a thorax and abdomen that are soft
  and flexible
• Many are covered in dense short, fine hairs
• Some have hardened heads that are visible, in
  
• others the head is retracted and not
  visible
• Two types of mandibles
  A) Moving against one
  another side to side
  
  B) Moving up and
  down parallel to each other

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Black Fly
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Chironomidae Midges
EXTREMELY common
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Tipulidae Crane flies

• Range in size from 0.5 to 3
• Fleshy and soft, grublike
• Gills and gill plate at end of abdomen

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Athericidae
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More True Flies
Phantom Crane Fly
Crane Fly
Blephariceridae
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Dragonflies and Damselflies (Odonata)

• All are Predators, morphological differences
  giving clues as to habitat niches

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Damselflies
Dragonflies
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Damselflies

• Six long, thin legs
• Three broad, oval gills at end of body
• No gills along side of body
• Abdomen not as wide as head

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Dragonflies

• Six long legs
• Spike-like tails
• Large eyes
• Thorax wider than head

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Gomphidae

• A family of dragonflies with stubby, flat,
  and short antennae
• The antennae project straight forward

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Coleoptera Beetles

• Aquatic larval adult beetles
• Diverse group
• Largest order of insects in the World

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Riffle Beetles

• Six jointed legs
• brown or black in color
• bodies hard

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Other common beetles
Psephenidae
Dytiscidae
Water Penny
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True Bugs (Hemiptera)

• Wide variety of shapes
• Piercing mouthparts (used for sucking juices)
• Hemiptera means half wing and refers to these
  insects having a wing that is half membranous and
  half hardened

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Crayfish (Decapoda)

• Non-insect arthropods
• 8 walking legs
• 2 pinching claws

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Scuds (Amphipoda)

• White or grey in color
• Their common name is Scuds or Side
  Swimmers
• Body is strongly flattened side to side and
  they have 5 pairs of legs

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Sowbug (IsopodaAsellidae)

• Dorsoventrally compressed
• Aquatic roly-poly

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Snails Limpets (Gastropoda)

• Snails are Mollusks with 1 shell
• Most are coiled and elongated, like a
  spiral staircase, except one family with
  the shell being a simple cone with no coils
• Adults usually have 4 or more coils

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Snails Limpets (Gastropoda)

• Coiled snails are either left-handed
  (sinistral), or right-handed (dextral)

• Important feature of the snail is the
  operculum (door or lid to the opening) which
  is present or absent

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Gilled snails (Right-handed)
Lunged snails (Left-handed and others)
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Segmented Worms (Annelida)

• Aquatic earthworms, leeches, etc.
• 3500 species worldwide
• 8 families in Maryland

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Maryland DNR Streamside Identification Techni
que
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Dragonflies and Damselflies
Exuviae
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Caddisfly adults
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Mayfly adults
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Stonefly adults
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Dobsonfly adults