Marine Bio Exam 3 (invertebrates)

What are marine arthropod’s exoskeletons made of?

Primarily made of chitin, a tough and flexible polysaccharide.

What is molting?

The process by which marine arthropods shed their exoskeletons to grow, allowing for the development of a larger, more complex body structure.

What is the telson of a horseshoe crab used for?

It is used primarily for anchoring and stability. It acts as a weapon for defense against predators and aids in flipping the crab upright if overturned.

What is the chelicera of a horseshoe crab used for?

The chelicera of a horseshoe crab is used for grasping and manipulating food, acting as a mouthpart that aids in feeding.

What are the segmentations of a horseshoe crab’s body?

It is segmented into the prosoma and opisthosoma

What do horseshoe crabs feed on?

They feed on detritus

What are horseshoe crab’s book gills used for?

The book gills of a horseshoe crab are used for respiration, allowing gas exchange in water, and also assist in locomotion by facilitating swimming.

How do sea spiders exchange gas?

They lack gills so they exchange gas through their legs by diffusion directly with the surrounding water.

How many pairs of eyes do Sea spiders have?

Sea spiders have five pairs of eyes that help them navigate their darker environment in the deep sea.

What are the special properties of a horseshoe crab’s blood?

What is the reproductive method of horseshoe crabs?

What is the common body plan of Crustacea?

Body is five or six segmented head, thorax, and abdomen

What type of larvae are crustaceans?

All crustaceans pass through the nauplius larvae stage whether embryonically or as free-living larvae.

How do barnacles exchange gas and filter feed?

They use cirri-modified gills that wave around to create a water current

What are cirri in barnacles?

Specialized appendages used for feeding via suspension

What are characteristics of copepods?

• They are the most dominant floaters in the ocean and can move relatively fast and make vertical migrations 

• They use their arms to create a water current to bring food in

• Rich in lipids

• Reproduce quickly

What are the similarities between ostracods and bivalves?

• Both have two-part shells (valves) that provide protection and support.

  • Filter feeders

Bioluminescence in ostracods…

Serves as a defense mechanism, a means of attracting mates, or a strategy to lure prey. The light is produced by chemical reactions within specialized cells or structures, and it can be used to communicate with other ostracods or to deter predators.

What subphylum do horseshoe crabs belong to?

Chelicerata

Give two examples of important crustacean zooplankton in pelagic food chains

Krill and copepods (type of zooplankton)

What are mandibles?

Jaw-like structures used for crushing and ingesting food

What is the sexual difference between male and female shrimp?

Males have petasma, and females have thelycum.

What is the adrostral sulcus in shrimp?

groove that flanks the rostrum and extends posteriorly, sometimes nearly reaching the end of the carapace (the hard outer shell).

What is the rostrum in shrimp?

A hard, beak-like structure that is a forward extension of the carapace (the hard outer shell) located in front of the eyes

Where do juvenile crab/shrimp spend their time?

Crabs are off shore, shrimp are near shore in estuaries/marshes

Where do adult crabs/shrimp spend their time?

Crabs are in the marshes/estuaries, shrimps are found off shore

What is the difference in structure for male vs female crab for the abdomen structure?

You can tell the difference between the sex of crabs based on how wide their abdomens females are broad, and males are narrow

What do all arthropods have?

• Exoskeletons

• They molt

• Open circulatory system w/ hemocyanin

• Compound eyes used for vision and is good at detecting movement

How do horseshoe crabs reproduce?

male crab hooks himself to the top of the larger female's shell by using his specialized front claws, and together they crawl to the beach. The female lays them in a nest in the sand.

Crustacean body plan consists of

• 5 segmented head, thorax, abdomen

• 2 pairs of antennae

• Mandibles for mouthparts

• 2 maxillae

How do barnacles reproduce?

They are hermaphrodites basically having an orgy.

How do acorn and gooseneck barnacles differ?

Acorn barnacles attach directly to surfaces with their, while gooseneck barnacles have a long, flexible stalk (peduncle) that attaches them to surfaces, resembling a goose's neck.

Importance of barnacles

Barnacles filter feed on plankton and other small organisms, filtering and cleansing large amounts of water for other organisms.

Stone crabs…

Can regenerate claw, competes with blue crab, doesn’t swim and tolerates high salinity

Where are stone crabs found?

Gulf Coast, Florida keys, and Atlantic Coast

Blue crab…

Have juveniles (have a red dot on claw) spend one month off shore, fifth leg modified for swimming, females release eggs in estuaries.

Importance of Blue Crab

Important predator in benthic environment

Feed on detritus, barnacles, mussels, oysters, and shrimp

Commercially and recreationally harvested

Mole crabs…

Burrow into sediment, utilize tidal movement and modified antenna for feeding, females lay eggs on the beach

How do mantis shrimp hunt?

They use their modified appendage to spear or smash prey, and they have color and UV spectra vision

Why is the krill life cycle successful? What is hindering their success?

They reproduce by dropping their eggs, which sink to the bottom, and metamorphosis and move up and use ice as protection. Due to climate change their reproduction faces a challenge.

Defining characteristics in Chelicerata?

Mouth parts are cherlicerae rather than mandibles

Book gills for respiration* (only in horseshoe crab)

Two pairs of eyes, 1 pair each of simple and compound

Orders of Chelicerata

Arachnids (terrestial)

Xiphosura (horseshoe crabs)

Pycnogonida (sea spiders)