Jenkins on ubuntu – how/where is it deployed

I'm a jee newbie so I may misunderstand some java concepts independent on jenkins itself.

I've got an access to a ubuntu-like server where jenkins was installed through sugo apt-get (someone else installed it). I've got a web access to the application. I want to find out how is it deployed and where – a tomcat (as a servlet container), an application server or nothing at all?

user@server:$ ps aux | grep jenkins
1001      1801  0.0  0.0   5628   836 pts/8    R+   10:58   0:00 grep --color=auto jenkins
jenkins  13758  0.1 11.0 1355676 456860 ?      Ssl  Feb05   1:26 /usr/bin/java -jar /usr/share/jenkins/jenkins.war --webroot=/var/run/jenkins/war --httpPort=8080 --ajp13Port=-1 --preferredClassLoader=java.net.URLClassLoader --logfile=/var/log/jenkins/jenkins.log

There is a .war file so there should be some kind of a servlet container, but I don't have tomcat installed.

user@server:$ dpkg -L jenkins
/.
/usr
/usr/share
/usr/share/doc
/usr/share/doc/jenkins
/usr/share/doc/jenkins/README.Debian
/usr/share/doc/jenkins/copyright
/var
/var/log
/var/log/jenkins
/var/lib
/var/lib/jenkins
/etc
/etc/logrotate.d
/etc/logrotate.d/jenkins
/etc/init
/etc/init/jenkins.conf
/etc/init.d
/etc/default
/etc/default/jenkins
/usr/share/doc/jenkins/NEWS.Debian.gz
/usr/share/doc/jenkins/changelog.Debian.gz
/etc/init.d/jenkins