Zoology Final Exam Study Guide

How many tagmata are Chelicerate bodies composed of? What are the names of the tagmata?

Primarily composed of 2 tagmata called the Prosoma/Cephalothorax and the Opisthosoma/Abdomen

What are the 3 types of appendages present in Chelicerates?

These appendages are called Chelicerae, Pedipalps, and Walking Limbs

What are the functions of Chelicerae?

They are the jaws/mouthparts used for prey capture and manipulation

  What are the functions of Pedipalps/palps?

A pair of elongated appendages that flank the mouth, are used for mechanoreception and chemoreception

  How can you tell the difference between an organism’s pedipalps and their chelicerae?

  Chelicerae are mainly used for feeding and have fangs, and pedipalps are elongated appendages that are used for receptions and sensing.

  How do Arachnids breath? What types of feeding strategies to Arachnids exhibit?

They breathe through the utilization of book lungs, and their feeding strategies are using silk and webs to trap prey, and they use their chelicerae to tear prey into small bits, insert digestive enzymes, and then they ingest liquefied food.

 Describe the general biology of Order Araneae. Describe how their chelicerae and pedipalps have been modified to fit their ecology.

  This Order’s chelicerae and pedipalps have been adapted. The chelicerae are standard, venom-injecting fangs. Their pedipalps are adapted to function as “antennae” that assist the spiders in sensing different objects.

  Describe the general biology of Subclass Acari. Describe how their chelicerae and pedipalps have been modified to fit their ecology.

  This Subclasses’ chelicerae and pedipalps have been adapted. Their chelicerae have 3 parts or can be modified as a hypostome to cut through a host’s skin. Their pedipalps are finger-like projections that are used for attaching and anchoring to hosts.

   What is a hypostome?

It is a harpoon-like structure that is calcified and permits parasitic ticks to attach and anchor to their hosts and suck blood

Describe the general biology of Order Scorpiones. Describe how their chelicerae and pedipalps have been modified to fit their ecology.

This Order’s chelicerae and pedipalps are modified. Their chelicerae are 3 parts and classified as chelate. Their pedipalps are long, chelate, and are mainly used for prey capturing and different manipulations.

  What is unique about the telson in Scorpiones?

   It is unique because it contains venom and a stinger for prey consumption.

What are some common scorpion taxa that may cause harm to humans?

  Some of these taxa are the Indian Red Scorpion, the Deathstalker, and the Arizona Bark Scorpion.

  What is molting/ecdysis? Why is this an important but potentially dangerous time within the life of a crustacean?

It is the shedding of the organism’s old exoskeleton, and it is potentially dangerous because a lack of the hard shell can make the organism vulnerable.

   Describe why crustaceans are known as “the most morphologically diverse” groups of animals in the world.

They are classified as this because they have many different unique and wide varieties of forms and structures.

  Describe the current taxonomic state of crustaceans. What is the evidence that crustaceans are paraphyletic?

A recent study has confirmed that crustaceans are categorized as paraphyletic. The evidence to support this is that Hexapods emerged within the Crustaceans and the Clade Pancrustacea.

  Describe the general biology, ecology, and morphology of an organism in the Order Isopoda.

They generally consume decaying or dead animal parts, but they can also be grazers, parasites and predators.

They also have uniramous appendages and a highly articulate skeleton that permits enrollment.

Contain about 10,000 species (5,000 terrestrial, 4,500 marine, and 500 freshwater).

   Describe the general biology, ecology, and morphology of an organism in the Order Stomatopoda.

  They are highly derived and unique, contain 126 species, all of which are marine.

They have complex behavioral patterns (fighting behavior), advanced visual systems.

They have two distinct feeding strategies, as well as raptorial appendages known as spearers and crushers. They even have a depth perception that is superior to humans.

   Describe the general biology, ecology, and morphology of an organism in the Order Amphipoda.

They lack a carapace, are dorsolaterally compressed, and are detritivores and scavengers found in marine, freshwater, and sometimes terrestrial environments. Their first two pairs of legs are usually modified into gnathopods, which are claw-like.

   Describe the general biology, ecology, and morphology of an organism in the Infraorder Caridea. What organisms are in this group?

They are found in salt and freshwater bodies worldwide, are generally classified as omnivorous, but some are filter feeders. They brood their eggs, and do not release them into the water. Shrimp and krill are in this group.

  Describe the general biology, ecology, and morphology of an organism in the Infraorder Brachyura. What organisms are in this group?

They can be found globally in saltwater, freshwater, and terrestrial environments. These crustaceans have a thick exoskeleton, and a rather robust pair of chelae/claws. Males have relatively larger claws, and the organisms in this group are fiddler crabs and decorator crabs.

Why are brachyurans called the “true crabs”? What other organisms are crab-like?

They are classified as “true crabs” since they evolved from the default family of crabs. Other organisms that are “crab-like” are hermit crabs.

  Describe the general biology, ecology, and morphology of an organism in the Infraorder Anomura.

  Classified as “other crabs,” or “not true crabs.” Can be found globally in terrestrial, salwater, and freshwater environments. Their “crab-like” appearances is due to homoplasy, or convergent evolution, carcinization.

   Describe the general biology of organisms in Class Remipedia. What organisms belong to this group?

  This Class contains crabs that are primarily blind and can be located in caves. They are known to be closely related to Hexapods, which makes them paraphyletic. Since they have venomous “fangs,” they are the only known venomous crustacean. The organisms belonging to this group are the Remipedes.

  Describe the general biology of organisms in Class Cephalocarida. What organisms belong to this group?

This Class contains organisms that are about 2-4 mm long, blind, and closely related to the Remipedes. They lack any form of eyes, have nine “legs,” and an elongated abdomen. They are primarily found inhabiting flocculent sediments. They resemble the most primitive crustacean fossils. This group contains the Horseshoe shrimps.

Describe the general biology of organisms in Class Branchiopoda? What organisms belong to this group?

This class is rather diverse, and they dominate freshwater habitats, are detritivores that feed on plankton using the setae on their appendages. The organisms in this group are the fairy shrimp, clam shrimp, and the tadpole shrimp.

  Describe the general biology and importance of Daphnia magna.

  Commonly classified as the “water fleas,” Daphnia magna can play the role of an important food source for larger animals, and they can assist in controlling and managing algae. This contributes to water stability and quality.

  Describe the general biology of organisms in Class Hexanauplia. What organisms belong to this group?

This Class was formerly grouped under the Maxxilopa polyphyletic class. They have a complex lifecycle, and are the most “crustacean-like” during their larvae stage. The organisms that belong to this group are the barnacles.

    What habitats are Crustaceans found in?

They are mostly diverse in marine habitats, but they can be found anywhere, such as terrestrial and freshwater habitats

  What type of feeding strategies do Crustaceans exhibit?

they are usually filter feeders, decomposers, scavengers, parasites, and predators of all kinds

Describe the steps of the crustacean molting cycle

The crustacean molting cycle contains these steps:

pre-molt (prepares the body for molting)

ecdysis

postmolt (body has soft texture)

intermolt (body regains hard texture)