Download iIINTRODUCTION TO ARTHROPODS

Lundkvist
Biology 11
iIINTRODUCTION TO ARTHROPODS
Read pages 607-616 in Miller & Levine and answer the following questions
___________
1. Complete the table below of the four subphyla of arthropods.
Subphylum Name
Anglosized Name of
Subphylum
Trilobites
Trilobitomorpha
Chelicerata
chelicerates
Example of animals that are included in the
subphylum
trilobites
Crustacea
crustaceans
Spiders, ticks, mites, scorpions, horseshoe
crabs
Crabs, shrimp and lobsters
Uniramia
Uniramians
Centipedes, millipedes & insects
2. The first arthropods appeared more than ___600 million_ years ago. Some arthropods have remained in
the _water_, where they have colonized all parts of the sea and most _freshwater___
habitats. Others were among the very first to colonize the __land__. The descendants of those pioneers were
on hand when the first __flowering plants____ appeared millions of __years_later.
The body form of the first _arthropods___ are thought to be similar to that of the _trilobites___ A typical
__trilobite___ body had a thick, __tough outer covering and was composed of many __segments_, each of
which bore a pair of __appendages___. Each _appendage_ was divided to from two branches, one a __walking
leg__ and one a featherlike _gill___.
Most living __arthropods____ exhibit two evolutionary trends away from the __trilobite__ form. First, many
have far fewer ___body segments__. The many ____segments__ found in their embryos fuse into larger
_segments_ during development. Second arthropod ___appendages___ have become increasingly
___specialized__ for __feeding_, _locomotion__ and other functions.
3. The three most important arthropod features are :
a) tough exoskeleton
b) jointed appendages
c) segmented body
___crustacea_
4. Other characteristics include: a) brain
b)Ventral nerve cord
c)open circulatory system
__uniramia__
___chelicerata__
Lundkvist
Biology 11
5. The _exoskeleton__ is a system of external supporting structures that are made primarily of the
carbohydrate __chitin__. Some exoskeletons, such as those of most insects are ___leathery___and
_flexible__ . Others, such as those of _ticks_ and _lobsters_ are extremely hard. These _exoskeletons_
provide excellent _protection_ from physical damage. Although the exoskeleton protects an
__arthropod’s__ body, it has the disadvantages you might expect from such a _covering___. Because an
__exoskeleton___is a solid coating, not a _living ____ tissue, it cannot __grow__ as the animal
_grows____.And __movement_ can occur only at the _joints_ of the _armour_.
6. All arthropods have __jointed_ appendages. (arthro- means __joint_; -pod, means _foot___)that enable
them to _move_. In primitive arthropods such as ___trilobites_, every body segment carries a single pair
or __appendages_. But in species in which body segments are _fused_together, some appendages have
been _lost___. Over millions of years, the remaining appendages have ____evolved_ into marvelously
versatile __adaptations_ to different __environments__. Arthropod appendages include __claws__,
__antennae___, walking legs, __wings__, ___flippers_ and other specialized structures.
7. All arthropods have __segmented___ bodies. Some, such as __milipedes__ and __centipedes__ have long,
wormlike bodies with many visible ___segments__. Others, such as insects, spiders and crabs have lost
some segments in the course of _evolution__.
8. Look on figure 28-8. What are the three body segments of the grasshopper? These are the three body
segments of all insects and spiders.
__head_
____thorax_______
_____abdomen______
__chelicerata__
__uniramia__
9. What types of modes of feeding are seen in arthropods? _herbivores, carnivores____________
___parasites, filter feeders, and detritus feeders________________________________
10. Arthropods have evolved three basic types of respiratory structures- _gills__, __book lungs & gills__ and
__tracheal tubes_. Many aquatic arthropods have __gills_ that look like a row of _feathers_ located just
under cover of their _exoskeleton___. Book gills (which are found in ___horseshoe crabs___) and _book
lungs__ (which are found in __spiders__ and their relatives) are unique to these arthropods. In both
these structures, several sheets of __tissue__ are _leyered__ like pages in a _book_. Most terrestrial
arthropods, __insects_, some __spiders____ and __millipedes__ for example have another ___respiratory__
device found in no other __animals_. From __spiracles__ long branching _tracheal tubes__ reach deep
into the animal’s tissues. The network of __tracheal__ __tubes_ supplies oxygen by _diffusion__ to all
body tissues. As the ___arthropods_ walk, fly or crawl, the __movement_ of their body muscles cause the
____treacheae__ to shrink and expand , pumping fresh air in and out of the __spiracles__.Tracheal tubes
work well only in __small__ animals; __large__ animals require a more _efficient_ way to deliver
_oxygen____ and remove _carbon dioxide__.
11. In arthropods a well developed _heart__ pumps blood through an_open___ circulatory system.
12. Complete the table of Excretion below
Lundkvist
Biology 11
Excretory Structure
Malpighian tubules
Arthropods that has it
Insects and spiders
Function
Bathed in blood inside sinuses and remove waste
Gills
Aquatic arthropods
Cellular wastes diffuse through from the body into
the surrounding water.
Found at the base of the antennae
lobsters
Green glands
13. Most arthropods have well developed _nervous system_. All have a __brain__ that consists of a pair of
___ganglia___ in the __head___. Arthropods have simple sense organs such as __statocysts_ and
___chemical___ receptors. Most arthropods also have sophisticated sense organs such as _compound eyes_
for gathering information from their ___environment__. Compound __eyes_ may have more than
_2000_ separate lenses and can detect __colour_ and __movement_ very well. Many insects can see
__ultraviolet_ light, which is __invisible__ to humans. Both __crustaceans__ and __insects__ have a welldeveloped sense of _taste__, although their _taste_ receptors are located in strange places. The chemical
receptors associated with the senses of taste and smell are located on the __mouthparts__, antennae and
__feet_. Many insects have well-developed ears that hear sounds above the __human__ range. Insect ears
are often in _odd_ places. The eardrums in grasshoppers, for example are behind their legs.
14. Why can many insects still walk or flap their wings after their heads are cut off? __________________
There are ganglia for each body part so if you remove one the other one can still move.
15. Describe movement in arthropods. ___ muscles generate force by contracting then transfer the force to
the exoskeleton.______________________________________________________________________
16. Reproduction in arthropods is ___simple__. Males and _females__ produce _sperm_ and eggs,
respectively, and fertilization usually takes place _inside_ the body of the female.
17. Why do arthropods need to molt? ____Exoskeletons don’t grow with the arthropod because it is not a
living tissue. As the arthropod grows it needs to molt_____
18. What is metamorphosis? ____A drastic change in form that occurs in arthropod
development_________________________
19. Fill in the subphylum of the arthropods below and all the other arthropod pictures on this worksheet:
___chelicerate__
__crustacea_ _
_uniramia__
__trilobite____