Marine Ecology Unit 4 - Benthos and Meiofauna

The most important environmental factor influencing the presence, absence, and types of interstitial organisms is:
a. light
b. temperature
c. salinity
d. grain size

Grain size

All of these are characteristics of seagrass beds except:
a. their borders are well-defined
b. they inhabit all types of substrates
c. they vary in the density of plants
d. they are restricted to a fairly narrow temp. range

D. They are restricted to a fairly narrow temp. Range

Which feeding type is quite rare among meiofauna due to lack of interstitial plankton?
a. suspension feeding
b. predation by other meiofaunal organisms
c. detritus feeding
d. predation by macrofaunal organisms

A. Suspension feeding

All of these statements regarding species richness (diversity) are true except
a. turbulent waters provide a means of meiofaunal transport
b. most meiofaunal organisms lack a motile larval phase
c. waterfowl provide a major means of meiofaunal transport
d. meiofaunal organisms exhibit the same polar to tropical gradient of abundance as macrofauna

d. meiofaunal organisms exhibit the same polar to tropical gradient of abundance as macrofauna

Benthos

Bottom-dwelling organisms.

Epifauna

Organisms that live on or above the substrate.

Sub tidal zone

below the intertidal zone on the continental shelf.

Kelp

Large, brown algae.

Stream Index

Calculated based off the relative abundance of different benthic macro invertebrate species.

Meiofauna

AKA intersasial organisms. Occupy the micro spaces between particles or live on individual particles. Infauna that are 0.5-0.062mm in size.

Infauna

Organisms that live in the substrate. Decided into categories based on size:
Macrofauna - Greater than 0.5mm.
Meiofauna - 0.5 to 0.062mm.
Microfauna - Smaller than 0.062mm.

Depositional Environment

The setting in which sediment is deposited

Anaerobic Environment

an environment without oxygen

Sea Anemone

Phylum: Cnidaria, same as jellyfish and coral. Known for symbiotic relationship with anemonefish.

Sea Cucumber

Type of echinoderm that help reduce ocean acidification by recycling calcium carbonate. Currently being overfished.

Crown-of-Thorns Sea Star

Up to 21 arms. Their surface is safe, despite their thorns. If you take them out of the water their body surface will burst and their liquid will drain out, causing their spines to flatten.

Carnivorous Sponges

Sponges (Phylum Porifera) are typically filter feeders. The deep sea Cladorhizidae
family, however, trap small crustaceans with velcro-like hooks.

Bull Kelp, AKA Giant Kelp

Kelp forests are an important ecosystem that supports high biodiversity. Due to its very fast growth rate, kelp is often used in a variety of products including food, toothpaste, pharmaceuticals and biofuels.

Peacock Mantis Shrimp

one of over 400 species of mantis shrimp, known for their incredible color vision and powerful claws. They have 16 color-receptive cones in their eyes (as opposed to our three) and can accelerate their attacking claws at 23 m/s.

Blue crab

Scientific name means "Beautiful Savory Swimmer". Very important economy in Chesapeake Bay. Sexually Dimorphic - Men have blue claws and narrow abdominal aprons which look like the Washington monument. Females have "painted nails", or red-tipped claws and broad abdominal aprons, which look like the capitol dome.

Pacific Cleaner Shrimp

36 genera of cleaner shrimp and over 150 species. Known for engaging in symbiotic relationships with fish, where they feed on insects and parasites living on the shrimp.

Echinoderms

Invertebrates with an internal skeleton and a system of fluid-filled tubes called a water vascular system. Over 6000 species including sea stars, sea urchins, and sea cucumbers. Most echinoderm larvae are planktonic with bilateral symmetry.

Cnidarians

Phylum including corals, anemones, jellyfish, and hydroids. About 9000 species, most of which have stinging tentacles. The stinging cells they possess are called chidocytes and contain a harpoon-like nematocyst that injects toxin into the venom.

Chidocytes

Stinging cells

Nematocyst

Harpoon-like structure in chidocytes that injects toxin into prey.

Mollusks

Over 50,000 species including Gastropoda (snails and sea slugs), Bivalves (clams, scallops, oysters), and Cephlapods (octopuses, squid, cuttlefish, and nautilus.) All mollusks have well developed bodies, but lack segmentation.

Anthropods

Largest phylum on earth. Over 1 million species, most of which are insects. Most marine anthropods are crustaceans, including crabs, lobsters, barnacles, and copepods. Crustaceans have an exoskeleton and five pairs of appendages, often with claws.

Sedimentary Communities

A sandy, unstable substrate. Organisms in the sedimentary sub tidal zone can be divided into two major groups:
Sediment destabilizers, or bioturbators who cause sediment to move or become disrupted.
Sediment stabilizers. These include various sea grasses whose roots bind sediments and restrict burrowing animals. These include mangroves.

Bioturbators

AKA sediment destabilizers. Organisms in sedimentary communities that cause sediment to become disrupted.

Sediment stabilizers

Organisms in sedimentary comminuted that include various seagrasses whose roots bind sediments and frequently restrict burrowing animals (competitive interference).

Surface Predators

Exposed at the surface and take organisms at or near the surface without disrupting the sediment structure.

Burrowing predators

Move down various tubes or channels provided by the deep-dwelling prey and attack them.

Digging predators

excavate holes to get food

infaunal predators

burrow through sediment and live in it at all times

rocky subtidal communities

not as common as sedimentary communities, have a hard substrate with low-growing encrusting plants and animals

Kelp beds and forests

In colder temperate regions, the hard subtudal substrates are dominated by very large brown algae known collectively as kelp. These associations are known as kelp beds if the algae do not form a surface canopy and kelp forests where there is a floating canopy.

Kelp bed

An association of kelp where the algae do not form a surface canopy.

Kelp forest

A community of kelp where the algae creates a floating canopy.

Holdfast

A root-like structure that anchors kelp.

Stipe

A stem-like structure of kelp which ends in one or more broad, flat blade.

Pnuematocyst

AKA a "float" which keeps the blade at the surface.

Seagrass

Flowering plants that have adapted to live submerged in water. All substrates are inhabited by these grasses, but the most extensive beds occur on soft substrate.

Seagrass beds

depositional environments, often with high organic content that can make the sediment under the bed anaerobic

Grain size

The most important factor in determining the presence, absence, and types of Meiofauna. The coarser the grain size, the greater the volume of interstitial space, and therefore the greater the size of Meiofauna.

Limiting factors of Meiofauna presence

Temperature - The most extreme range of temperature occurs in intertidal beaches and minimally in sub-tidal sediments.
Salinity - Particularly in intertidal areas where freshwater runoff occurs.
Wave action - both inter-tidally and sub-tidally affecting the arrangement of movement.

Statocyst

An organ that detects gravity and helps meiofauna differentiate up and down.

Adaptations of Meiofauna:

Statocyst - Organ which determines up and down
Simpler anatomy - reduction in cell number
Vermiform shape - elongated, wormlike
Neoteny - retention of larval form
Naptic - ability to cling to grains by an adhesive material or hooks and claws
Efficient reproduction - short life cycles, few gametes

Sponge Phylum

Porifera

Coral, sea anemone, siphonophores phylum

Cnidaria

Flatworms, flukes, tapeworms phylum

Platyhelminthes

Roundworm phylum

Nematoda

Segmented worms phylum

Annelida

Chitons, snails, bivalves phylum

Mollusca

Crabs, shrimps, barnacles phylum

Anthropoda

Sea stars, sea urchins, sea cucumbers phylum

Echinodermata

Fish, tunicates phylum

Chordata